Patent Description:
For many years dimensional inspection (i.e. measurement) of gears and gear-like workpieces (e.g. cylindrical and bevel gears, worms) has mostly been carried out by two different methodologies, namely, (<NUM>) functional testing comprising meshing a gear or other toothed workpiece with a known master gear or mating gear, and (<NUM>) analytical testing using a coordinate measurement machine (CMM) or a gear measurement machine (GMM) such as the GMS line of gear measurement machines manufactured by, and commercially available from, the Applicant.

Functional testing compares the measurement of a work piece against a master gear or a mating gear. Functional testing platforms for gears (i.e. roll testers) include those testers known as double flank testers and single flank testers. With single flank testing, mating gears roll together at their proper (fixed) center distance with backlash and with only one flank in contact. Gears can be tested in pairs or with a master gear. With double flank testing, mating gears are rolled together in tight mesh which produces contact on both flanks. A work gear is meshed with master gear. By providing various encoders on the platform, the relative movement of gears (i.e. center distance variation) making up a collection or summary of gear errors is captured. For example, on a typical double flank gear roll testing machine, a work piece (e.g. cylindrical gear) is meshed with a known master part (e.g. cylindrical gear) and rotated. One of the gears is mounted on a fixed axis and other is mounted on a floating axis. The linear displacement between the axes is measured when the two gears are rotated. Composite errors from this functional testing, such as center distance variation, are reported and compared against required tolerances. Such a roll tester is also capable of reporting characteristics related to the size of gear teeth such as tooth thickness and diameter-over-pins (DOP).

A typical CMM or GMM utilizes at least one contact probe. In recent years, a non-contact sensor (e.g. laser) has been used to inspect some gears as is disclosed in <CIT>, the disclosure of which is hereby incorporated by reference. A contact probe is positioned at programmable locations on a gear tooth surface to measure its deviation from a theoretical tooth surface. A non-contact probe emits light on the tooth surface of a gear at a desired location to determine the same deviation.

Analytical testing of gears may be done by either a GMM or CMM. These machines include a computer-controlled apparatus which includes a high-resolution touch sensor (e.g. tactile probe) and/or a non-contact probe. The machine of <CIT> is an example of an analytical machine for inspecting a gear workpiece utilizing a touch sensor and/or a laser sensor for inspection. Both sensors require repeatable positioning of the sensor for reliable and accurate measurement at desired locations on the gear tooth surface.

CMM and GMM machines are both equipped with probes capable of measuring the location of points on the surface of workpieces. This is one of the core functions of these machines and is used to implement the full range of functionality available on these machines (e.g. measuring size, location, deviation from theoretical surface and form of geometric shapes). These measurements are checked against certain tolerances to ensure the correct fit and function of the measured workpieces.

To measure a workpiece, the machine must convert the signal output from its probe (or probes) and the respective position of the relevant machine axes into the location of points on the surface of a workpiece. For this reason, the orientation of sensors to properly approach desired areas of a gear and the accurate calibration of sensors are very important. When a workpiece is changed to another workpiece having a different geometry, the positions of sensors will likely require adjustment for accurate measurement of the "different geometry" workpiece.

In metrology systems such as disclosed by <CIT>, at least one non-contact sensor and preferably two non-contact sensors are utilized to measure gear artifacts. Preferably, two lasers are located in a manual set-up fixed position on a post and are oriented in such a way that each laser measures one flank of a gear.

Prior art <FIG>, <FIG> and <FIG> show a machine <NUM>, of the type as disclosed by <CIT>, comprising at least one non-contact sensor assembly <NUM> on a functional testing platform for workpiece inspection and/or measurement. The machine <NUM> comprises a base portion having a top portion <NUM> (preferably a flat plate), production gear <NUM> (i.e. the workpiece) and master gear <NUM> mounted on respective workholding arbors <NUM> and <NUM>, such as mechanical, hydraulic or pneumatic arbors as is known to the skilled artisan. A slide plate <NUM> is affixed to slide <NUM> and arbor <NUM> is positioned on plate <NUM>. The production gear <NUM> may be located on either the left hand side or on the right hand side of the master gear <NUM> but is shown on the left side in <FIG>. The gear <NUM> rotates about a motorized axis W via motor <NUM>. The master gear <NUM> is mounted on right hand side (axis T) and is not motorized. The rotation of master gear <NUM> is provided by the driving motor <NUM> for axis W and the engagement with the production gear <NUM>.

For functional testing, the master gear <NUM> is on a slide <NUM> (X axis) and is moveable in the direction of the X axis (preferably horizontal) to allow coupling and decoupling of gears. Decoupling is required so that the production gear <NUM> can be removed and replaced with different workpieces either manually or via automation means. A linear scale <NUM> (<FIG>) is mounted to capture movement of the slide <NUM> in the X axis direction during operation. A rotary encoder <NUM> is mounted below the motorized production gear <NUM> (axis W) to capture rotary movement of the workpiece gear. Inputs of the rotary encoder and the linear scale are captured so that during rotation of gear pair, relative movement of gears (in the X direction) is measured with respect to the rotary position of the workpiece gear <NUM>.

As shown in <FIG>, a non-contact sensor such as an optical sensor, for example a laser assembly <NUM>, is positioned on left side of the machine for analytical testing. A single laser <NUM> is mounted on a linearly adjustable post <NUM> having an adjustable mounting mechanism <NUM> whereby the laser <NUM> is movable and positionable in up to three linear directions X, Y, Z (preferably mutually perpendicular) and in up to three rotational directions, that is, about each of X, Y and Z for manually setting the operating position of the laser. In other words, laser <NUM> is preferably capable of six degree-of-freedom movement but only for set-up purposes. Such adjustability is preferable in order to orient the laser emission line <NUM> onto a gear tooth space whereby it can capture at least a portion of the tooth involute (i.e. profile direction) from root-to-tip for both tooth flanks of adjacent teeth.

However, the only computer-controlled axis on the machine of <FIG> for analytical testing is the workpiece rotational axis W. The machine lacks the ability to re-position the probe via movement along and/or about one or more linear axes. Computer controlled positioning of a workpiece <NUM> relative to laser <NUM> via motion along or about one or more mutually perpendicular directions or axes X, Y and Z (i.e. three dimensional) is not possible and, hence, computer-controlled calibration of laser <NUM> via motion along or about one or more mutually perpendicular directions or axes is also not possible.

<CIT> discloses a shape measurement device and a shape measurement method involving a measurement path setting unit determining a shape measurement program on the basis of a measurement path to specify a time schedule of a direction and velocity of the movement of an optical probe along the measurement path, and also a column being linearly movable in a plane orthogonal to its extension direction and rotatably carrying a L-form holding member which itself rotatably carries the optical probe, wherein rotatability of the second rotation becomes around a differently oriented axis but still an axis within the same plane when the column is linearly moved between two alternative positions for bringing the position of the first axis of rotation into conformity with one of two reference spheres.

The present invention provides for a gear measuring and/or inspecting machine with the features of claim <NUM> and a gear processing machine with the features of claim <NUM>. The machine comprises a multi-directional positioning system, and hereafter sometimes features of the machine are expressed as features of the positioning system. A sensor is positionable via the system comprising movement in linear directions and rotary directions so as to control linear and/or rotational movement of a sensor automatically to a predetermined position without operator intervention. The multi-directional positioning system allows faster setup times when a workpiece or tooling on a machine is changed.

The multi-directional positioning system is operable to provide linear motion in two directions (i.e. linear motions) and rotational/angular motion about two axes (i.e. rotary motions) with position feedback (e.g. linear and/or rotary encoders) which are controlled by motors (e.g. stepper or servo) to move each sensor in the necessary direction or directions whereby the sensor is properly positioned in order to measure a desired surface on a workpiece such as the tooth surface of a gear.

The terms "invention," "the invention," and "the present invention" used in this specification are intended to refer broadly to all of the subject matter of this specification and any patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of any patent claims below. The subject matter should be understood by reference to the entire specification, all drawings and any claim below. The invention is capable of other constructions and of being practiced or being carried out in various ways, as long as said constructions and ways remain within the scope of protection defined by the appended claims.

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 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. The use of letters to identify elements of a machine, method or process is simply for identification and is not meant to indicate importance or significance, or that the elements/steps should be performed in a particular order.

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 unless specifically recited.

The invention comprises a multi-axis positioning system capable of moving a sensor and a workpiece relative to one another and addresses the heretofore inability to adequately re-position a sensor automatically, particularly a non-contacting sensor such as an optical sensor, particularly a laser sensor, with respect to a workpiece such as a gear, shaft or other toothed article (collectively referred to hereafter as "gear"), using linear and rotary axes with no intervention from the machine operator.

The inventive multi-directional positioning system is shown in a first embodiment by <FIG> where two positioning systems <NUM> are illustrated in order to accommodate two non-contact, preferably optical (e.g. laser) sensors <NUM> for measuring a workpiece <NUM>. One sensor is positioned to scan tooth flanks on one side of the workpiece teeth and the other sensor is positioned to scan tooth flanks on the opposite side of the workpiece teeth as can be best seen in <FIG> wherein a laser emission line <NUM> is shown projecting from each sensor <NUM>. While the following description of the inventive position system will refer to only one positioning system <NUM>, it is understood that the description applies equally to additional positioning systems such as both positioning systems <NUM> in <FIG>.

Positioning system <NUM> comprises a column <NUM> on which slide <NUM> is positioned for Z-direction movement (preferably vertical as viewed in normal operation) on column <NUM> via guide rails <NUM>. Column <NUM> is attached to a rotary base <NUM> which is rotatable, as shown by arrow RA, about axis A (preferably oriented vertical as viewed in normal operation) thereby enabling column <NUM>, and sensor <NUM>, to be angularly adjustable/rotatable about the A-axis (see <FIG>). Base <NUM> is positioned on slide <NUM> which is movable in the X-direction (preferably horizontal as viewed in normal operation) on a base plate <NUM> via guide rails <NUM> (<FIG>, <FIG>) so as to position column <NUM> in the X-direction. Direction Z lies in a first plane which, as normally viewed, is vertical (i.e. the plane of the page of <FIG>) and direction X lies in a second plane which, as normally viewed, is horizontal (i.e. the plane of the page of <FIG>) with the first and second planes being perpendicular to one another. Directions Z and X are perpendicular to one another. The A-axis is parallel to the Z direction, may lie in the first plane, and is perpendicular to the X-direction. Base plate <NUM> is preferably attached to top portion <NUM> of the machine base.

A rotatable mounting plate or disc <NUM> (i.e. rotary stage) is attached to slide <NUM> and is angularly adjustable/rotatable, as shown by arrow RB, about axis B (preferably oriented horizontal as viewed in normal operation, see <FIG>, <FIG>) via a motorized drive or a worm and wheel drive for example. Preferably, the B-axis extends parallel to the second plane and is perpendicular to, intersects, and is angularly movable about the A-axis during the angular adjustment RA of column <NUM> about the A-axis (<FIG>). Laser sensor <NUM> is positioned on mounting plate <NUM> whereby the sensor is angularly adjustable/rotatable about the B-axis. A braking mechanism, preferably a disc brake mechanism comprising a caliper <NUM> and brake disc <NUM>, is preferably associated with rotary base <NUM> and/or rotatable mounting plate <NUM> for stopping rotary motion and securely maintaining the angular position of the rotary base <NUM> and/or rotatable mounting plate <NUM> during operation of the sensor. While the disc brake mechanism is preferred, other braking and/or clamping mechanisms may be utilized.

Different motions, or combinations of motions, may be performed by the positioning system <NUM>, or elements thereof, in order to accommodate different workpiece geometries or the change from one workpiece geometry to another workpiece having a different geometry. Some examples (non-exhaustive list) include:.

With a sensor, or sensors, suitably positioned, the workpiece may be measured accurately.

Movement of each of slide <NUM> in direction Z, column <NUM> in direction X, column <NUM> about axis A, mounting disc <NUM> about axis B and workpiece rotation about axis W is imparted by separate drive motors such as, for example, servo or stepper motors or worm and wheel drives (not 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 respective motors is preferably associated a feedback device such as a linear or rotary encoder (not shown) as part of a CNC system which governs the operation of the drive motors in accordance with instructions input to a computer controller (i.e. CNC) which may be a dedicated computer control for the positioning system <NUM> or, for example, the computer control for a functional testing platform of the type shown in <FIG>.

<FIG>, <FIG> and <FIG> show two of the inventive positioning systems <NUM> located on a functional testing platform <NUM> of the type shown in <FIG>. For simplicity and ease of viewing, elements such as slide plate <NUM>, slide <NUM> and linear scale <NUM> have been omitted. However, instead of a non-contact sensor, such as a laser assembly <NUM>, requiring manual setup of axes positions to achieve the appropriate operating position relative to a workpiece <NUM> located on the functional testing platform <NUM>, the inventive positioning system <NUM> automatically achieves the appropriate operating position of the non-contact sensor (e.g. laser) <NUM> relative to workpiece <NUM>. The operating positioning being accomplished via the previously described positioning system comprising linear and rotational motions to automatically move the sensor to a predetermined position without operator intervention.

<FIG> shows two functional testing platforms <NUM> arranged in an end-to-end manner whereby the inventive position system <NUM> (two shown) is located between the respective workpiece spindles <NUM> of the testing platforms. In this arrangement, one of the positioning systems <NUM> can be utilized to position a sensor relative to a workpiece on one platform <NUM> (e.g. right side in <FIG>) and the other positioning systems <NUM> can be utilized to position a sensor relative to a workpiece on the other platform <NUM> (e.g. left side in <FIG>). The ability of the positioning system <NUM> to be angularly positionable about the A-axis and linearly movable in the X-direction enable such functionality. Alternatively, both positioning systems <NUM> may be directed to a workpiece on one spindle, (e.g. right-side as shown in <FIG>), and then both positioning systems may be redirected to a workpiece on the other spindle (e.g. left-side spindle of <FIG>).

<FIG> shows an arrangement of functional testing platforms <NUM> similar to <FIG> but with the inclusion of two sets (total of <NUM>) positioning systems <NUM> wherein two positioning systems <NUM> are dedicated to the right-side functional testing platform and two positioning systems <NUM> are dedicated to the left-side functional testing platform. In the embodiment of <FIG>, two X-direction-oriented positioning systems share one set of X-direction guide rails <NUM>.

While the above discussion has been directed to a positioning system for appropriately positioning a non-contact sensor, such as an optical sensor, for example a laser, relative to a workpiece, the inventive positioning system may also be operated in an active manner during a scanning (e.g. measuring/inspection) process. The positioning system may be operated to reposition the non-contact sensor during scanning in order to reposition the sensor, either continually, incrementally and/or intermittently, whereby a greater portion of a gear tooth flank surface in the profile direction (i.e. tooth height) and/or in the lead direction (i.e. tooth length) may be scanned compared to the scanned area of a fixed position sensor.

Although the preferred orientation of axes (i.e. A, B) and directions of motion (i.e. X, Y) of the positioning system <NUM> are shown in <FIG>, the invention is not limited thereto. For example, as best explained with reference to <FIG>, X-direction motion of the position system <NUM> relative to a workpiece <NUM> may be effected by the master gear <NUM> and workpiece <NUM> being movable in the X-direction instead of X-direction movement of the positioning system <NUM>. Alternatively, X-direction movement capability may be included with the positioning system <NUM> as well as with the master gear <NUM> and workpiece <NUM>.

While the inventive positioning system has been discussed and illustrated in association with a functional testing platform for gears, the positioning system is not limited thereto. The inventive positioning system <NUM> may be associated with (e.g. located on) other types of machine tools such as, for example, other gear manufacturing machines such as gear cutting machines (e.g. hobbing, power skiving) or gear finishing machines (e.g. grinding, honing, power skiving, hard skiving, polishing). The X-direction of travel may function for infeeding and withdrawing a non-contact sensor, or another tool, relative to a workpiece.

Additionally, the positioning system may be modified to include a workpiece spindle <NUM> such as shown in <FIG> thereby creating a standalone non-contact measuring apparatus for gears and/or other toothed articles.

<FIG> represents a gear manufacturing cell <NUM> such as a hard finishing cell wherein a testing machine, such as the functional testing platform <NUM> of <FIG>, is one component of the cell. In the example of a hard finishing cell, block <NUM> represents a gear processing machine for finishing a previously cut workpiece. Examples of finishing include grinding (e.g. threaded-wheel and/or profile grinding), honing, power skiving, hard skiving, finish hobbing, and polishing. An automation system <NUM>, preferably a robotic system, for loading and unloading both machines <NUM> and <NUM>, and transferring workpieces between the machines, is located between the gear processing machine <NUM> and the testing platform <NUM>. Automation system <NUM> may also include additional devices for performing auxiliary processes such as, for example, part washing, laser marking, sorting, measuring and part handling in a stackable basket system. The gear manufacturing cell may be an automated closed-loop cell wherein part measurement information, particularly out-of-tolerance measurements, obtained by the functional testing platform <NUM> is communicated to the gear processing machine <NUM> and any process adjustments are automatically made to the operational settings of the gear processing machine to correct the detected deficiencies in the machined part. Preferably, <NUM> percent of parts processed by the machine <NUM> are measured and/or tested by the functional testing platform <NUM>.

Although the gear manufacturing cell <NUM> of <FIG> has been discussed with regard to hard finishing, it is not limited thereto. Alternatively, the gear manufacturing cell <NUM> may be configured for non-hard finishing machining (e.g. "rough" or "soft" machining, collectively referred to hereafter as "soft") wherein block <NUM> represents a machine for performing a soft operation such as , for example, rough (initial) hobbing, face milling or face hobbing of bevel gears, power skiving (soft), shaping and shaving. The soft gear manufacturing cell may also be an automated closed-loop cell wherein part measurement information, particularly out-of-tolerance measurements, obtained by the functional testing platform <NUM> is communicated to the gear processing machine <NUM> and any process adjustments are automatically made to the operational settings of the gear processing machine to correct the detected deficiencies in the machined part. Preferably, <NUM> percent of parts processed by the machine <NUM> are measured and/or tested by the functional testing platform <NUM>.

The soft machining cell may further include means for chamfering and/or deburring a workpiece produced by a soft operation. Chamfering and/or deburring units may be incorporated within the machine <NUM> or the manufacturing cell may include an additional machine for chamfering and/or deburring. <FIG> shows an example of such a manufacturing cell <NUM> wherein block <NUM> represents a chamfering and/or deburring machine. Automation system <NUM>, preferably a robotic system, performs loading and unloading of machines <NUM>, <NUM> and <NUM>, and transfers workpieces between the machines. Such a soft manufacturing cell may also be configured as an automated closed-loop cell with <NUM> percent inspection of workpieces as discussed above.

Claim 1:
A gear measuring and/or inspecting machine comprising,
a multi-directional positioning system for positioning a workpiece measuring and/or inspection non-contact sensor (<NUM>) on the measuring and/or inspecting machine, the multi-directional positioning system comprising an automatic system, the multi-directional positioning system comprising a column (<NUM>), a rotary base (<NUM>) and a slide (<NUM>) positioned on said column, the sensor being mountable on said slide (<NUM>),
said sensor being positionable via said automatic system comprising movement in at least two linear directions and at least two rotary directions so as to control linear and rotational movement of said sensor automatically to a predetermined position without operator intervention to measure a desired surface on a toothed workpiece, wherein the movement in the two linear directions comprises movement in a first linear direction Z by means of said slide (<NUM>) positioned on said column (<NUM>) for Z-direction movement and movement in a second linear direction X by means comprised in said machine,
wherein directions Z and X are perpendicular to one another and wherein the movement in the two rotary directions comprises movement in a first rotary direction RA about an axis A and movement in a second rotary direction RB about an axis B, wherein axis A extends parallel to the Z direction and axis B extends perpendicular to and intersects axis A, wherein the column (<NUM>) is attached to said base (<NUM>), the machine comprising means for rotating the sensor around the second rotary direction RB,
characterized in that said movement of the sensor (<NUM>) in the first rotary direction RA is enabled by base (<NUM>) being a rotary base rotatable about said axis A thereby enabling column (<NUM>) and sensor (<NUM>) to be angulary rotatable about said A-axis.