DESC:FIELD OF INVENTION

The present invention relates to apparatus for measuring bores of machined components. In particular, the present invention relates to apparatus for measuring internal radii of partial bores. More particularly, the present invention relates to an apparatus with self-expanding collet on a concentric parent bore for measuring internal radii of partial child bores with respect to the parent bore in machined components.

BACKGROUND OF INVENTION

Often, there are limitations while machining and carrying out the subsequent assembly process requiring partial guide bores to be made in components to be machined. This means, inside a machine, a shaft-like structure requiring a guide to support and guide it, may not surround it all around (i.e. 360°), but surround it only partially (90° to 120°). In such cases, although the required diameter is critical (in the tolerance range of 0.015 mm.) for the component being machined, only 25-30% area is available on it for the probe to check it.

Normally, such components are machined on a conventional CNC-controlled Horizontal Machining Center (HMC). The component is hydraulically clamped, and a high-speed, high-accuracy spindle motor with different dynamically balanced tools/machines/mills having different bores/faces is required. In the present case under consideration, the tools used are single-point boring bars and reamers. In such cases, conventional practice is to use Co-ordinate Measuring Machines (CMMs) to probe intermittent points on such partially machined bores and to generate a best-fit circle or to use Roundness Testers for probing the entire bore for its radius and geometric form. The measurement accuracy of both these checking methods relies on a combination of hardware and software used, which usually do not provide the true form of the circle, thereby leads to errors (standard deviations and form errors).

PRIOR ART

US4383368A discloses a bore concentricity gauge having a collet at one end adapted to be expanded into close fitting engagement with one of two axially spaced bores on a workpiece and a hollow concentricity plug at its opposite end adapted to be received in close fitting engagement with the other bore. The plug has an accurately concentric bore therein adapted to be engaged by a rotatable "go" bushing journaled on a mandrel having an expander for the collet thereon.

US 2651845 A discloses a roundness checking gauge for a work piece comprising a collet in which the work piece to be tested is rotatably received including split rings for exerting pressure radially inwardly on the work piece; and reed supported means urged into contact with the work piece for transmitting the movements caused by work piece diameter variations to be imposed on a measuring device.

US 5182865 A discloses an apparatus for measuring workpiece concentricity having a base, a concentricity spin fixture, a spring-biased shaft, a collet, a follower member, and a concentricity indicator. The concentricity spin fixture receives a collet which receives workpieces of varying shank diameters and drive profiles. A follower member designed to engage a specific workpiece drive profile is biased against the workpiece drive profile by the spring-biased shaft. A test operator measures concentricity by rotating the workpiece using the concentricity spin fixture and by measuring the movement of the follower member against the spring-biased shaft using the concentricity indicator. The apparatus can measure the concentricity of workpieces with a shank and a drive profile, such as screws, bolts, other fasteners, and punches.

DISADVANTAGES WITH THE PRIOR ART

However, there are several problems associated with the conventional gauges disclosed in prior art documents discussed above. These disadvantages are briefly discussed below:
The bore concentricity gauge having disclosed in US4383368A can check for concentricity, however involves high stack values due to an array of machined assembly components, which lead to an expected self-runout / concentricity of up to 0.015 mm to cause impermissible measurement errors. Torque has a crucial role, which skews final result. Moreover, there is no method to correct or reduce the self-runout or concentricity except to machining within very stringent tolerances, which adds to the overall component cost and without eliminating the minimum stack. Thus, this gauge cannot be used for blind or tight-fit parent bores and perpendicularity cannot be checked anywhere with respect to bore in which it is inserted. Further, this gauge concerns checking the complete bores having different surface forms such as splines, et cetera. This gauge outputs in attribute form based on tightness of fit based on the actual enlargement and bushing.

The roundness checking gauge disclosed in US2651845A checks only for OD roundness and there is not any reference made to checking a secondary bore. Further, this gauge uses a collet to grip the rollers for checking the roundness by gripping the workpiece through a collet on its ID, while the reading is communicated to the measuring device by the OD of the collet. This leads to some inherent out-of-roundness or non-concentricity in the collet rings itself. Moreover, this gauge checks only the roundness. Readings are transferred from the collapsed collet rings to the measuring device via ID-OD interaction, but for achieving this, ID-OD must be true to each other, which is not possible due to manufacturing limitations.

The collet disclosed in US5182865A is used only for guiding and gripping the workpiece. It relies on a spring actuated master form to engage with the workpiece, the master form then communicates via follower to indicate out of roundness, which is achieved on positive locking of the concave and convex profiles. This apparatus also uses multiple machined components to the least count in a range of about 0.015 mm. This apparatus checks only for positive or negative form, such as face run-out et cetera and nowhere mentions a secondary bore in variable data. Also, none of the above citations mention the possibility of checking partial child bores.

It was noticed that during machining, the following failures occurred:

• Boring bar being a single point cutting tool got out of balance due to the bore being partially machined.

• Reamer bottomed out and created an oval/non-concentric bore.

• After any of the above possibilities have occurred, the only way to ascertain the acceptable quality is by checking/probing the bores all around the cylinder circumference.

• If the bore is a complete bore, (3600), a conventional dial bore gauge can be used. However, for partial bores, a conventional CNC-controlled Horizontal Machining Center (HMC) and normal tools used here are single-point boring bars and reamers.

• Since normal dial bore gauge relies on a spring-loaded shaft, which expands and sets itself or aligns with the bore diameter being checked every time, there should be pressure on either side of the probe ends, which is impossible in such a partial cylindrical bore.

• Since the bore is not complete, the pressure cannot be applied to the diametrically opposite probes of the gauge.

• These partially bored components not complying with the specifications may even lead to a premature failure of the assembly in the field, thereby directly affecting the customer, the goodwill of the manufacturer.

• So, while the complete guide bore can be checked with a conventional variable dial bore gauge, the partial entity child bore can have no such provisions, and since it is not complete bore and applying pressure to the diametrically opposite probes of this dial gauge is not possible, which is the crux of the problem here.
• Since the partially bored components not complying with the specifications could not be checked 100% before forwarding for further assembly, unavoidable rejections may occur at the assembly stage.

As shown in Figure 1, firstly, the complete parent guide bore which is a complete cylindrical bore closed at one end, is machined first. Subsequently, the child bore which is a partial bore made along the wall and concentric with the complete parent guide bore. However, during machining, the following failure modes are possible:

The undesirable possibilities like boring bar becoming unbalanced due to machining a partial bore or the reamer bottoming out and creating an oval/non-concentric bore can only be checked by ascertaining that the acceptable quality is properly checked for the bores all around the circumference of the cylinder thereof.

If a bore is complete (i.e. 360°), then a conventional variable dial bore gauge is used. Here, this can be achieved by 100% inspection of all bores being machined.

However, the problem being faced while inspecting partial bores can only be explained once we understand how a complete cylindrical bore is checked.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an apparatus for checking the radii of partial bores machined in components.

Another object of the present invention is to provide a cost-effective apparatus for checking the radii of partial bores machined in components.
Still another object of the present invention is to provide an apparatus for checking the radii of partial bores machined in components, which has better accuracy and precision of measurement.

Yet another object of the present invention is to provide an apparatus for checking the radii of partial bores machined in components, which offers high repeatability and reproducibility.

A further object of the present invention is to provide an apparatus with the expandable collet gauge system for checking the radii of partial bores in machined components with almost infinite adjustability.

A still further object of the present invention is to provide an apparatus for checking the radii of partial bores machined in components, which has simple functioning by compensating for manufacturing limitations.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an apparatus for checking and measuring radii of partial (child) bore with respect to a concentric (parent) guide bore machined in a component, wherein the apparatus comprises:

• a collet gauge system including:

- a collet gauge;
- a collet cap;
- a dial clamp;
- a dial probe; and
- a first plurality of Allen bolts, preferably two Allen bolts for assembling the gauge system; and

• a master assembly for making the gauge system true therewith, the master including:

- master ring;
- a master ring base; and
- a second plurality of Allen bolts for assembly of the master;

wherein the collet gauge system placed on the master assembly and tightened thereon by a plurality of Allen bolts, preferably four Allen bolts, is made true by using the dial probe placed along the partial (child) bore on the master ring of the master assembly.

Typically, after making the collet gauge system true on the master assembly, the self-expanding-contracting collet gauge system is made concentric with the complete (parent) guide bore at the bottom thereof for acting as a reference for checking and accurately measuring the radii of the partial (child) bore machined in the components, preferably gearbox housings.

Typically, the collet gauge system is configured as a self-expanding-contracting collet gauge system according to the form of the complete (parent) guide bore in which it is to be inserted for checking and measurement of the partial (child) bore made in the machined components, preferably gearbox housings.

Typically, the self-expanding-contracting collet gauge system comprises appropriate cross-sections of geometric features, e.g. the slits and relieved undercuts according to the required strength and deflection to match the form of the complete (parent) guide bore in the machined components, preferably gearbox housings.

Typically, the self-expanding-contracting collet gauge system expands or contracts uniformly about its cylindrical form or diameter by maintaining the geometric center thereof irrespective of its expansion or contraction in the presence or absence of pressure thereon.

Typically, the collet cap functions to hold the dial probe and the center of the dial probe is aligned with the center of the collet disposed below it and the collet cap is made adjustable.

Typically, the master ring base maintains the perpendicularity of the collet gauge system with the complete (parent) guide bore on the master ring by assembly thereof with the master ring by means of the second plurality of Allen bolts, preferably four Allen bolts.

Typically, the Allen bolts are sealed to ensure gauge repeatability and reproducibility (R&R) to retain the consistency of measurement of the collet gauge system.

Typically, the collet cap bolted on the collet gauge by means of two Allen bolts and the dial clamp screwed into the collet cap form a dial holder for holding the probe dial disposed perpendicular to the collet gauge top surface for expanding or contracting the collet gauge under the pressure exerted by the complete (parent) guide bore.

Typically, the pressure exerted by the complete (parent) guide bore for contracting the collet gauge makes the centers thereof concentric with each other and the collet gauge to superimpose on itself the geometric form of the complete (parent) guide bore to check and precisely measure the radii and geometric form of partially cylindrical (child) bore with respect to the complete (parent) guide bore machined in the components, preferably gearbox housings.
DESCRIPTION OF THE INVENTION

Accordingly, an apparatus for checking partially machined radii in machined components with respect to concentric guide bore is developed to overcome the abovementioned disadvantages of the existing bore radii measurement gauges.

The idea underlying the present invention is to design and develop such an apparatus, which is concentric with the complete parent guide bore (full cylindrical bore) at the bottom, which can be used as a reference to check the other concentrically machined partially bored child bore for its correct radius and geometric form under normal product machining conditions.

This is achieved in accordance with the present invention by using the concept of an expanding-contracting collet as shown in Figures 5 and 6.

The inventive apparatus does not include any multiple-machined components, but only one single collet, which can expand or contract with high accuracy and precision, and offers high gauge repeatability and reproducibility (R&R) of up to 0.002 mm. It requires no external force to operate the collet except that exerted by the parent guide bore. This apparatus can achieve near zero concentricity, since it has an infinite adjustability feature, however practically up to 0.002 mm concentricity is attainable.

The inventive apparatus uses a self-expanding collet, expanding without any external force. It satisfies the stiffness and deflection criteria in order to expand or contract according to the bore in which it is inserted. Because of the absence of any expanding setup, the system can be used in tight-fit conditions in which parent bore is blind. Here, the collet base and master take care of perpendicularity issues.

This gauge system configured in accordance with the present invention can accurately measure the radius and geometric shape of the partial bores.

The values displayed on the dial are variable and can be interpreted for size and geometric form, the repeatability checking possible with this system is of the order of 0.002 mm, thus making it superior to any other existing gauge system.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings.

Figure 1 shows the isometric view of the apparatus configured in accordance with the present invention, while working within the component being checked after boring operation.

Figure 2 shows the isometric detailed view of the apparatus of Figure 1 during operation in cooperation with the master for making it true therewith.

Figure 3 shows another isometric view of the apparatus configured in accordance with the present invention, while working within the component being checked after boring operation, labelled with the detail constructional features thereof.

Figure 4 shows the isometric detailed view of the apparatus of Figure 3 during operation in cooperation with the master for making it true therewith.

Figure 5 shows an exploded isometric view of the apparatus configured in accordance with the present invention along with the master thereof.

Figure 6 shows the top view of the apparatus configured in accordance with the present invention and marked with a section line A-A’ therein.

Figure 7 shows the sectional view of the apparatus of Figure 6 depicting its cross-section cut along the section line ‘A-A’ marked therein.

DETALED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows the isometric view of the apparatus with a with self-expanding -contracting type collet gauge 100 configured in accordance with the present invention, while checking a component, i.e. gearbox housing 10 after boring operation and shown with a partial (child) bore 12 with reference to a complete (parent) guide bore 14.

Figure 2 shows the isometric detailed view of the collet gauge 100 of Figure 1 during its truing operation in cooperation with the master assembly 200 thereof.

Figure 3 shows another isometric view of the apparatus with a self-expanding collet gauge 100 of Figure 2 while working within a gear box 10 being checked after boring operation therein and labelled with its constructional features including a gauge 102, a collet cap 104, a dial clamp 106, a dial 108 and two Allen bolts 110.

Figure 4 shows the isometric detailed view of the collet gauge 100 of Fig. 3 during its operation in cooperation with a master assembly 200 for making it true therewith. The collet gauge 100 includes a gauge 102, a collet cap 104, a dial clamp 106, a dial 108, master ring 112, and master ring base 114 and four Allen bolts 116.

Figure 5 shows an exploded isometric view of the apparatus, i.e. self-expanding collet gauge 100 disposed over the master assembly 200 as shown in Figure 4. Here, collet gauge or gauge 102, a collet cap 104, a dial clamp 106, a dial 108, master ring 112, and master ring base 114 and four Allen bolts 116. The gauge 102 is the expanding-contracting type collet designed as per the strength and deflection with appropriate cross-sections of geometric features like slits and relieved-undercuts with most uniform fit to match with the form of the complete parent guide bore in which it is inserted. As the name suggests, the collet 102 expands or contracts uniformly about its cylindrical form or diameter, while maintaining the geometric center thereof, even when it is expanded or contracted under pressure. Here, the pressure to contract the collet is exerted by the full cylindrical bore, i.e. the complete parent guide bore. This makes the center of the collet and the complete parent guide bore to be concentric and the collet superimposes on itself the geometric form of the complete parent guide bore. The collet cap 104 acts as the holder for the dial 108. It is necessary that the center of the probing dial 108 is same as the center of the collet 102 disposed below it. For this purpose, an utmost simple and elegant configuration is used by making the collet cap 104 adjustable by making the counter bores on the collet cap 104 bigger, to facilitate making it true with the collet gauge system 100 placed on the master 200 and then tightening it by two Allen bolts 110. With this, setting the collet gauge system 100 with the dial probe 108 can be made true along the partial (child) bore on the master 200. Before handover to the production unit, Allen bolts 110 are sealed to avoid the loss of concentricity of the collet gauge system 100. The dial clamp 106 holds the dial 108 in place. Further, the master ring 112 is configured to replicate the component, here gearbox 10 under checking (however, this may vary from one component to the other). The master ring base 114 maintains the perpendicularity of the collet gauge system 100 with the complete (parent) guide bore 14 on the master ring 112 and this is assembled as a master system 200 by four Allen bolts 116. The only important aspect for obtaining gauge repeatability and reproducibility (R&R) is to ensure that the sealing of the locking Allen bolts 110 is never tampered with. By maintaining the sealing, the apparatus configured in accordance with the present invention retains its measurement consistency.

Figure 6 shows the top view of the apparatus configured in accordance with the present invention configured with the collet cap 104, dial clamp 106, a dial 108 and Allen bolts 110 and marked with a section line ‘A-A’ thereof.

Figure 7 shows the sectional view of the apparatus configured in accordance with the present invention depicting the cross-section cut along the section line ‘A-A’ and depicting the assembly of the collet gauge 102 with collet cap 104, dial clamp 106 and dial 108. Accordingly, the apparatus 100 can be effectively used for inspecting radii and geometric form of partially cylindrical (child) bore, which are concentric to another (parent) bore. The dial holder is made of two parts: one that screws onto collet cap 104 and the other dial clamp 106 that screws onto the collet cap 104 to hold on to the dial 108. This apparatus can be used pre-dominantly in gearbox housings, which are made compact, while completely retaining their strength and functionality.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The apparatus with self-expanding collet for measuring internal radii of partial child bores with respect to concentric parent bore in machined components has the following technical and economic advantages:

• Usable for checking the radius and geometric form of partial (child) bores with respect to another concentric complete (parent) guide bore.

• Simple and elegant configuration and functioning by compensating for manufacturing limitations.

• Includes a gauging system with an expanding-contracting collet gauge to superimpose on itself, the geometric form of the complete (parent) guide bore, in which it is inserted.

• Configurable according to the strength and deflection with appropriate cross-sections of geometric features like slits and relieved-undercuts for achieving superior accuracy and precision.

• Provides high gauge repeatability and reproducibility (gauge R&R) in cases where conventional bore dial gauges can never be used or where interpolation methods give inconsistent results.
• Avoids exorbitant costs of precision manufacturing, which was otherwise necessary and which is easily dispensed with by allowing the self-expanding-contracting collet gauge system to have almost infinite adjustability to true itself on its respective master.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of this invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention.

These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel.

Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures. ,CLAIMS:We claim:

1. An apparatus for checking and measuring radii of partial (child) bore with respect to a concentric (parent) guide bore machined in a component, wherein the apparatus comprises:

• a collet gauge system including:

- a collet gauge;
- a collet cap;
- a dial clamp;
- a dial probe; and
- a first plurality of Allen bolts, preferably two Allen bolts for assembling the gauge system; and

• a master assembly for making the gauge system true therewith, the master including:

- master ring;
- a master ring base; and
- a second plurality of Allen bolts for assembly of the master;

wherein the collet gauge system placed on the master assembly and tightened thereon by a plurality of Allen bolts, preferably four Allen bolts, is made true by using the dial probe placed along the partial (child) bore on the master ring of the master assembly.

2. Apparatus as claimed in claim 1, wherein after making the collet gauge system true on the master assembly, the self-expanding-contracting collet gauge system is made concentric with the complete (parent) guide bore at the bottom thereof for acting as a reference for checking and accurately measuring the radii of the partial (child) bore machined in the components, preferably gearbox housings.

3. Apparatus as claimed in claim 1, wherein the collet gauge system is configured as a self-expanding-contracting collet gauge system according to the form of the complete (parent) guide bore in which it is to be inserted for checking and measurement of the partial (child) bore made in the machined components, preferably gearbox housings.

4. Apparatus as claimed in claim 3, wherein the self-expanding-contracting collet gauge system comprises appropriate cross-sections of geometric features, e.g. the slits and relieved undercuts according to the required strength and deflection to match the form of the complete (parent) guide bore in the machined components, preferably gearbox housings.

5. Apparatus as claimed in claim 4, wherein the self-expanding-contracting collet gauge system expands or contracts uniformly about its cylindrical form or diameter by maintaining the geometric center thereof irrespective of its expansion or contraction in the presence or absence of pressure thereon.

6. Apparatus as claimed in anyone of the claims 1 to 5, wherein the collet cap functions to hold the dial probe and the center of the dial probe is aligned with the center of the collet disposed below it and the collet cap is made adjustable.

7. Apparatus as claimed in claim 1, wherein the master ring base maintains the perpendicularity of the collet gauge system with the complete (parent) guide bore on the master ring by assembly thereof with the master ring by means of the second plurality of Allen bolts, preferably four Allen bolts.

8. Apparatus as claimed in claim 7, wherein the Allen bolts are sealed to ensure gauge repeatability and reproducibility (R&R) to retain the consistency of measurement of the collet gauge system.

9. Apparatus as claimed in claim 1, wherein the collet cap bolted on the collet gauge by means of two Allen bolts and the dial clamp screwed into the collet cap form a dial holder for holding the probe dial disposed perpendicular to the collet gauge top surface for expanding or contracting the collet gauge under the pressure exerted by the complete (parent) guide bore.

10. Apparatus as claimed in claim 9, wherein the pressure exerted by the complete (parent) guide bore for contracting the collet gauge makes the centers thereof concentric with each other and the collet gauge to superimpose on itself the geometric form of the complete (parent) guide bore to check and precisely measure the radii and geometric form of partially cylindrical (child) bore with respect to the complete (parent) guide bore machined in the components, preferably gearbox housings.

Dated: this day of 26th October 2016. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT