US3902283A

US3902283A - Gem grinder with approach control means

Info

Publication number: US3902283A
Application number: US434415A
Authority: US
Inventors: Philip D Bean
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-18
Filing date: 1974-01-18
Publication date: 1975-09-02
Anticipated expiration: 1992-09-02

Abstract

A gem polishing machine having a rotatable flat lap with a dop mounted above the lap and movable to polish the gem on the abrasive surface of the lap. Sensor means are provide to signal force applied to the gem and with an ultimate stop to end the cycle.

Description

United States Patent [191 Bean 1 1 Sept. 2, 1975 [54] GEM GRINDER WITH APPROACH 2,971,263 2/1961 Rockafellow 51/l69.75 X CONTROL MEANS 3,724,138 3/1973 lshikawa 5l/165.8

[76] Inventor: Philip D. Bean, 3253 S. 162nd St.,

Seattle, Wash. 98188 [22] Filed: Jan. 18, 1974 [21] Appl. No: 434,415

[52] US. Cl. 5l/125.5; 51/165.75; 51/165.8; 51/229 [51] Int. Cl. B24B 9/16 [58] Field of Search 51/165 R, 165.75, 165.77,

[56] References Cited UNITED STATES PATENTS 2,829,472 4/1958 Salzer 51/229 X Primary Examinerl-larold D.. Whitehead Attorney, Agent, or FirmRoy E. Mattern, Jr.

[5 7] ABSTRACT means are provide to signal force applied to the gem and with an ultimate stop to end the cycle.

10 Claims, 8 Drawing Figures PATENTEUSEP 2197s 3, 9 02,283

sum 1 (IF g FORCE a4 AMPLIFIER 82 FIG. 4

PATENTEBSEP 2|97s 3. 902,283

SHEET 2 UF 2 FACET CUTTING METER DEVIVCE LIGHTS DOPSTICK STOP DIGITAL TRANSDUCER AMPLIFIER AUD'BLE OTHER. FIG 5 GEM GRINDER WITH APPROACH CONTROL MEANS BACKGROUND OF THE INVENTION Previously, when precision gem faceting machines or other machines were being used by skilled craftsmen to cut and/or to polish diamonds and/or other valuable gem stones, the gem stones were mechanically positioned in predetermined selected index position for movement toward the surface of an abrasive turntable, so facets could be formed in a perfect geometric arrangement. During such movement, either a mechanical control assembly or a manual pressure assembly was used to urge the gem stone against the abrasive cutting surface until a limit actuator means, such as electrical contacts or a mechanical stop, were contacted Therefore, the precision of a faceting or shaping operation has been dependent on the sensitivity and repeatability of these limit positioning or limit actuating means. Even slight unwanted tolerances or movements or deflections created as mechanical pressures or forces over-stress the limit positioning means, may re sult in flaws being created in cut and/or polished gems. Therefore in the past, the gem cutter has had to rely on his or her finely developed finger touch and/or to use a hearing sound cutting method to cut and/or polish gem surfaces or shapes. Extensive and repeated careful inspections, therefore were frequently undertaken as the cutting and/or polishing was being performed, in order to stay within limits of polishing or cutting. The use of most stops, in the past, have created an abrupt signal which does not enhance the craftsmans sense of feel. Moreover, there are variances in pressures re quired, as hard and soft faces of the same gem stone are being cut or polished during final stages of polishing. Therefore there has been a need to create a greater sensitivity to both pressure and movement during concluding cutting of rough or final forms and polishing, and this electro-mechanical position sensing subassembly incorporating strain gages has been developed.

SUMMARY OF THE INVENTION In several embodiments electro-mechanical position sensing subassemblies, incorporating strain gages and- /or proximity sensor components, are provided to create the greater sensitivity to both pressure and movement that is necessary during concluding cutting of rough or final forms and polishing of surfaces of gems, when using machinery, such as faceting machines or gem faceters, When these embodiments are installed and observed, forces of one gram or less are easily monitored, and movements as small as a few or, five or less millionths of an inch are readily detected. In one embodiment, the circuitry of the strain gages in a wheatstone bridge arrangement is coupled with an electronic amplifier read out meter to present a continuous calibrated visual display or read out during the last five ten-thousandths of an inch of movement of the gem stone toward the cutting wheel, skaif, or lap, and before the final or ultimate mechanical stop is reached. Therefore the approach to the ultimate stop is indicated, rather than the abrupt arrival at the ultimate stop. In this way, the electro-mechanical position sens ing and indicating subassembly, complements and increases the operators control and his or her sense of touch as he or she views, for example, the needle of an electronic amplifier read out meter swinging toward the indicated full or ultimate stop position while he or she is removing very small amounts of material from the diamond, or gem stone giving him or her a very accurate indication of the speed at which the ultimate stop limit pin is being approached.

In another embodiment, proximity sensor components are incorporated, in lieu of strain gages, in circuitry which alters the electrical energy delivered to electronic units, such as a gage having an easily observed sweep hand or needle. These embodiments, using either the strain gages or proximity sensors, are arranged for use during the concluding shaping of either rough or finished facet surfaces. Also, both of these embodiments, with necessary modifications, become additional embodiments which are adapted to being installed at another position on machinery, such as faceting machines and gem faceters, for use during the concluding shaping of either rough or finished marquis, pear, oval, heart, antique cushion, emerald and other shapes.

DRAWINGS OF PREFERRED EMBODIMENTS FIG. 1 is a perspective view ofa gem cutting, shaping, and polishing machine, referred to as a faceting machine, equipped with the electro-mechanical position sensing and indicating subassemblies;

FIG. 2 is a partial side view of the faceting machine indicating the relationship of the movement of the end of the dop stick holding the gem stone during machine operations, to the movement of the needle on the indi cating read out meter of the electromechanical position sensing and indicating subassemblies;

FIG. 3 is a partial transverse view with portions sec tioned to indicate how the dop shaft or arm housing at its end opposite to the dop stick holding the gem stone, is moved against the pick up .and sensing elements of the electro-mechanical position sensing and indicating subassembly which incorporates strain gages mounted on a cantilevered beam;

FIG. 4 is a schematic circuit diagram of the electromechanical position sensing and indicating subassembly utilizing strain gages;

FIG. 5 is a schematic block diagram indicating how a facet cutting machine or faceting machine with an electro-mechanical position sensing and indicating subassembly, centering on the use of a dop shaft or arm stop transducer, using, as necessary, an amplifier, may selectively be matched to a meter, light system, digital read outs, audible sound generators and/or other ob servable indicators to aid the operator of the gem forming machine or faceting machine during production of a perfect gem;

FIG. 6, is a partial perspective view of the gem cutting, shaping and polishing machine, referred to as a faceting machine, indicating another embodiment of components of the electro-mechanical position sensing and indicating subassemblies used in conjunction with control cams, which are in turn employed to control cutting and polishing marquis, pear, oval, heart, antique cushion, emerald and other shapes;

FIG. 7 is a partial transverse view, with portions shown in section, of how this dop shaft or arm stop transducer is mounted with its strain gages, and the subassembly is employed during the cutting and polishing of marquis, pear, oval, heart, antique cushion, cmerald and other shapes;

FIG. 8 is a partial transverse view, with portions shown in section, of how, in lieu of a deflection beam with strain gages, a proximity sensor is utilized to indicate the small movements occurring as the dop shaft or arm is concluding its intended movement, either during the early or follow on cutting or polishing steps, to create, for example, the perfectly formed facet on a gem.

DESCRIPTION or THE PREFERRED EMBODIMENTS The various illustrated embodiments of the electromechanical position sensing subassemblies are shown in conjunction with gem cutting and polishing machines 22 generally referred to as faceting machines, shown in FIG. I, which position a gem stone 24, for precise, repeatable angle approaches to a revolving flat rotatable disk 26, known as a lap. It has a selectable type of abrasive surface materials, which together are also referred to as a cutting wheel or skaif. A valuable gem stone 24 is secured to a dop or dop stick 28 and then by a collect or chuck subassembly 30 to a dop spindle housing assembly 32 and in turn to the angular positioned pivot body 34. A curved support 36 with a radial adjustment protractor scale 38, together generally referred to as the protractor 36 slidably receives a partially overlapping top housing generally referred to as a facet angle setting assembly or saddle block 40 which rotatably holds the pivot body 34, and therefore ultimately pivots the dop 28. The saddle block 40 is movable along the protractor 36, upon movement of a facet angle adjusting mechanism, not shown. Also the protractor 36 is secured to a supporting member 42. It in turn is slidably positioned on a vertical adjustment support subassembly 44 equipped with precise height adjustment calibration actuators and adjusters 46 utilizing micrometer height dials, referred to as the micrometer vertical adjustment. Center portions 48 of this vertical support subassembly 44 are selectably and firmly mounted to the base 50 in adjustable positions along slide retainer 52 of the facet cutting and polishing machine 22, and outer portions 54 thereof slide on the center portion 48. The base 50 rotatably supports the splash pan or housing 56 in which the lap 26 revolves. The lap mounting spindle or shaft 58 with its securement nut 60, is driven below within the base 50 by a drive shaft of an electric motor and guided in precision bearings, not shown. Also not shown, for clarity, are lights and a subassembly for supplying cutting and pol ishing liquids to the lap, wheel, or skaif 26.

Approaching a Specified Angle Utilizing Strain Gages As shown in FIG. 1, in this particular embodiment, the eIectro-mechanical position sensing and indicating subassembly 20, uses an electronic amplifier read out meter 64 to indicate, by movement of a sweep hand or needle 66, the concluding gram of force and/or the concluding increments of movements, in reference to the motions of the dop or dop stick 28, as, for example, when a first rough cut, or a finishing polishing operation, is being concluded in reaching the intended surface or shape, as specified, in reference to the particular forming of a gem 24. This is illustrated further in FIG. 2, after the overlapping top housing or saddle block 40 is secured at its intended angular position on the protractor 36, the dop 28 and its various supporting

subassemblies

30, 32, 34, is pivoted about its pivotal mounting 68 to the saddle block 40 to cause the cutting or polishing of a gem stone 24, upon the relative movement of the lap 26. Then, for example, during the concluding 0.001 inch of forming, in view of the 2X to 1X, pivotal mounting 56 location, the 0.0005 inch of movement to the ultimate stop 58 is accurately sensed, as further indicated in FIG. 3.

The pivot body 34, which rotatably receives the dop spindle housing assembly 32 and which is pivotally attached to the saddle 40 by using the pivotal mounting 68, has a formed protruding abutment 70 which ultimately bears against the cylindrical or pin ultimate stop 72. Yet before the firm ultimate contact occurs, there is a range of an initial and adjusting contact made with an adjustable advanced probing pin 74 which is movably retained in the stop 72. As shown in FIG. 3, the probing pin 74, which is a screw, threadably secured in a cantilevered beam structure 78 mounted within the ultimate stop 72 secured to or a part of the saddle block 40. Mounted on the cantilevered beam structure 78 are strain gages 80 which are strained upon the movement of the cantilevered beam structure 78.

As indicated in FIG. 4, the changes in stress of the strain gages 80, create an unbalance in the active circuitry 82 which is sensed and thereafter indicated on the amplifier or read out meter 64, upon movement of the sweep hand or needle 66.

Approaching a Specified Contour Utilizing Strain Gages Many of the same electro-mechanical position sensing subassembly 20, components are also utilized during the approach to a specified contour in another embodiment used when cutting or polishing a gem stone 24 to obtain a specific shape, using cams to control the cutting and/or polishing operations to reach marquis, pear, oval, heart, antique cushion, emerald and other shapes. In FIG. 6, one of these earns 90 is shown removably secured near the top of the dop shaft 92. When rotative and pivotal movement of the dop shaft 92 and dop stick 28 is occurring to form a gem from a gem stone 24 to match the cam controlled shape, as the contour of the cam is approached, an advanced, retractable plunger 96, protruding beyond the ultimate stop structure 98, is first contacted. Ultimate stop structure 98 in FIG. 7 is secured to or apart of saddle block 40 of FIGS. 1 and 3. As illustrated in FIG. 7, retractable plunger 96 butts up against and contacts the cantilevered beam 100 near its end. Strain gages 80 are installed on the cantilevered beam 100 which is fastened to ultimate stop structure 98 by means of fasteners 102. The circuitry 82 and these strain gages 80 are protected under cover 104, and the circuitry 82 is utilized in the same way, as illustrated in FIG. 4 to indicate the deflection of the beam 100, etc. The resulting movement of the sweep hand 66 on meter 64 is observed by the person forming the gem from the gem stone 24 and as a consequence he or she forms the gem perfectly.

Approaching Specified Angles or Contours Utilizing Proximity Sensors In the same gem machining environments, the person forming the gem, using electro-mechanical position sensing subassemblies, also achieves better results when, in lieu of strain gages 80 and circuitry 82, proximity sensors 108 are installed with their circuitry I10, as illustrated in FIG. 8. For example, referring to FIGS.

2 and 8, as the abutment 70 on pivot body 34, with its magnetically attracted insert 112 moves toward the proximity sensor 108, installed in ultimate stop 114, which in turn is secured to or a part of saddle block 40, the signals generated are indicated on the electronic amplifier read out meter 64, upon movement of the sweep hand 66. Also, as indicated in FIG. 5, the approach to the ultimate stop may be observed by using lights, digital readings, audible signals, and/or other signals.

Other Components Noted for Better Understanding in FIGS. 1, 2 and 6, some features, perhaps best referred to as prior art features, are illustrated; however, they are not directly pertinent in reference to the use of the electro-mechanical position sensing and indicating subassembly 20. For example, index lever 116, pivots at 118 to clear its locking end 120 from the radial facet stops 122 on the index gear 124. Also a precision worm gear device, known as a cheater or splitter, 126 is used to turn the dop spindle housing subassembly 32 and thus the gem stone 24 on its own axis, providing further refining adjustments to the radial index of facets.

SUMMARY OF ADVANTAGES When gem cutting and polishing machines also known as gem faceters, or faceting machines are improved by the addition and/or incorporation of electromechanical position sensing and indicating subassemblies centering on components such as strain gages and- /or proximity sensors, the following advantages are realized: the fear of overcutting is eliminated; the alignment of the potential facet of the gem to the polishing or cutting surface is accurate; the interim inspection times are greatly reduced with a corresponding decrease in fatigue and eyestrain; the operators sense of touch is enhanced giving him or her a higher degree of sensitivity and more opportunity for repeatable accuracy; the range of approach via the various means, such as the meter needle movement, is accurately presented during the given concluding cutting or polishing operations, throughout a finite range before an ultimate abrupt mechanical stop is reached, and the rate of removal of the material is at the same time well indicated; sound cutting methods no longer need to be practiced; more delicate operations, free of excessive manual operating forces, are undertaken; moreover, the electromechanical position sensing and indicating subassem blies are readily incorporated into more extensive automatic control assemblies; and throughout the entire use of these electromechanical position sensing and indicating subassemblies, there are the savings in time during the making of repeated precision facet cuts, and there are the ultimate savings realized by avoiding the spoiling of a gem by overcutting and/or over polishing.

I claim:

1. A gem cutting and polishing machine, comprising:

a. a base;

b. a fiat rotatable disc or lap, mounted upon the base,

for mounting selectable abrasive surfaces;

c. a pivot body support structure, mounted upon the base, comprising in turn;

1. a pivot shaft with axis parallel to the lap plane;

2. an ultimate stop structure;

3. a structure which supports the ultimate stop structure and pivot shaft, and which can be ad justed to control the height of the pivot shaft above the lap and the angle between the lap plane and an axis running from the pivot shaft to the ultimate stop structure;

d. a pivot body, mounted rotatably upon the pivot shaft in such a way that its rotation in one or both directions past a certain point is blocked by the ultimate stop structure;

e. a dop, mounted in part within the pivot body, ro-

tatable about an axis normal to the axis of the pivot shaft, and having at one end a structure to firmly grip the gem stone to be cut or polished;

f. a sensor to detect and to signal the concluding motions of the pivot body or dop as it approaches and finally contacts the ultimate stop structure;

g. electrical circuitry to transfer the sensor signals to a signalling device h. a signalling device to present to the user of the machine information such as the force being applied to the gem, the rate of cutting, or the distance remaining before a desired surface or shape of the gem is reached.

2. A gem cutting and polishing machine, as claimed in claim 1, wherein the sensor is comprised of one or more strain gages.

3. A gem cutting and polishing machine, as claimed in claim 1, wherein the sensor comprises a flexible, longitudinal member, affixed at or near one end to the pivot body support structure and situated so as to be contacted and flexed by a portion of the pivot body or of the dop during the concluding movements of the pivot body or dop leading up to the pivot body or dop contacting the ultimate stop structure, and a plurality of strain gages attached to the flexible member to detect and signal deflections of the member.

4. A gem cutting and polishing machine, as claimed in claim 1, wherein the sensor is comprised of one or more proximity sensors.

5. A gem cutting and polishing machine, as claimed in claim 1, wherein the sensor is comprised of a proximity sensor, secured to the pivot body support structure, and situated so as to be approached and finally contacted by a magnetized portion of the pivot body or dop or by a magnet affixed to the pivot body or dop, as the pivot body or dop approaches and finally contacts the ultimate stop structure.

6. A gem cutting and polishing machine, comprising:

a. a horizontal base;

b. a flat, rotatable disc or lap, mounted upon and parallel to the base, for mounting selectable abrasive surfaces;

0. a vertical adjustment support subassembly, substantially longitudinal in shape, mounted upon the base with longitudinal axis normal to the base, adjustable in position on the base in directions parallel to the base plane, and finely adjustable in height above the base plane;

d. a protractor support member, slidably mounted on the vertical adjustment support subassembly;

e. a protractor, consisting of a circular segment mounted by means of the protractor support member in a plane normal to the base plane;

f. a saddle block, mounted slidably upon the protractor, a portion of said saddle block serving as an ultimate stop structure;

g. a pivot shaft, mounted upon the saddle block, with the axis of the pivot shaft parallel to the base plane;

h. a pivot body, mounted rotatably upon the pivot shaft in such a way that its rotation in one or both directions past a certain point is blocked by the ultimate stop structure;

i. a dop, mounted in part Within the pivot body, rotatable about an axis normal to the axis of the pivot shaft, and having at one end a structure to firmaly grip the gem stone to be cut or polished;

j. a sensor to detect and to signal the concluding motions of the pivot body or dop as it approaches and finally contacts the ultimate stop structure;

k. electrical circuitry to transfer the sensor signals to a signalling device l. a signalling device to present to the user of the machine information such as the force being applied to the gem, the rate of cutting, or the distance remaining before a desired surface or shape of the gem is reached.

7. A gem cutting and polishing machine, as claimed in claim 6, wherein the sensor is comprised of one or more strain gages.

8. A gem cutting and polishing machine, as claimed in claim 6, wherein the sensor comprises a flexible, longitudinal member, affixed at or near one end to the pivot body support structure and situated so as to be contacted and flexed by a portion of the pivot body or of the dop during the concluding movements of the pivot body or dop leading up to the pivot body or dop contacting the ultimate stop structure, and a plurality of strain gages attached to the flexible member to detect and signal deflections of the member.

9. A gem cutting and polishing machine, as claimed in claim 6, wherein the sensor is comprised of one or more proximity sensors.

10. A gem cutting and polishing machine, as claimed in claim 6, wherein the sensor is comprised ofa proximity sensor, secured to the pivot body support structure, and situated so as to be approached and finally contacted by a magnetized portion of the pivot body or dop or by a magnet affixed to the pivot body or dop, as the pivot body or dop approaches and finally contacts the ultimate stop structure.

Claims

1. A gem cutting and polishing machine, comprising: a. a base; b. a flat rotatable disc or lap, mounted upon the base, for mounting selectable abrasive surfaces; c. a pivot body support structure, mounted upon the base, comprising in turn; 1. a pivot shaft with axis parallel to the lap plane; 2. an ultimate stop structure; 3. a structure which supports the ultimate stop structure and pivot shaft, and which can be adjusted to control the height of the pivot shaft above the lap and the angle between the lap plane and an axis running from the pivot shaft to the ultimate stop structure; d. a pivot body, mounted rotatably upon the pivot shaft in such a way that its rotation in one or both directions past a certain point is blocked by the ultimate stop structure; e. a dop, mounted in part within the pivot body, rotatable about an axis normal to the axis of the pivot shaft, and having at one end a structure to firmly grip the gem stone to be cut or polished; f. a sensor to detect and to signal the concluding motions of the pivot body or dop as it approaches and finally contacts the ultimate stop structure; g. electrical circuitry to transfer the sensor signals to a signalling device h. a signalling device to present to the user of the machine information such as the force being applied to the gem, the rate of cutting, or the distance remaining before a desired surface or shape of the gem is reached.

2. an ultimate stop structure;

3. a structure which supports the ultimate stop structure and pivot shaft, and which can be adjusted to control the height of the pivot shaft above the lap and the angle between the lap plane and an axis running from the pivot shaft to the ultimate stop structure; d. a pivot body, mounted rotatably upon the pivot shaft in such a way that its rotation in one or both directions past a certain point is blocked by the ultimate stop structure; e. a dop, mounted in part within the pivot body, rotatable about an axis normal to the axis of the pivot shaft, and having at one end a structure to firmly grip the gem stone to be cut or polished; f. a sensor to detect and to signal the concluding motions of the pivot body or dop as it approaches and finally contacts the ultimate stop structure; g. electrical circuitry to transfer the sensor signals to a signalling device h. a signalling device to present to the user of the machine information such as the force being applied to the gem, the rate of cutting, or the distance remaining before a desired surface or shape of the gem is reached.

6. A gem cutting and polishing machine, comprising: a. a horizontal base; b. a flat, rotatable disc or lap, mounted upon and parallel to the base, for mounting selectable abrasive surfaces; c. a vertical adjustment support subassembly, substantially longitudinal in shape, mounted upon the base with longitudinal axis normal to the base, adjustable in position on the base in directions parallel to the bAse plane, and finely adjustable in height above the base plane; d. a protractor support member, slidably mounted on the vertical adjustment support subassembly; e. a protractor, consisting of a circular segment mounted by means of the protractor support member in a plane normal to the base plane; f. a saddle block, mounted slidably upon the protractor, a portion of said saddle block serving as an ultimate stop structure; g. a pivot shaft, mounted upon the saddle block, with the axis of the pivot shaft parallel to the base plane; h. a pivot body, mounted rotatably upon the pivot shaft in such a way that its rotation in one or both directions past a certain point is blocked by the ultimate stop structure; i. a dop, mounted in part within the pivot body, rotatable about an axis normal to the axis of the pivot shaft, and having at one end a structure to firmaly grip the gem stone to be cut or polished; j. a sensor to detect and to signal the concluding motions of the pivot body or dop as it approaches and finally contacts the ultimate stop structure; k. electrical circuitry to transfer the sensor signals to a signalling device l. a signalling device to present to the user of the machine information such as the force being applied to the gem, the rate of cutting, or the distance remaining before a desired surface or shape of the gem is reached.

10. A gem cutting and polishing machine, as claimed in claim 6, wherein the sensor is comprised of a proximity sensor, secured to the pivot body support structure, and situated so as to be approached and finally contacted by a magnetized portion of the pivot body or dop or by a magnet affixed to the pivot body or dop, as the pivot body or dop approaches and finally contacts the ultimate stop structure.