US2142415A - Worm polishing machine - Google Patents

Description

Jan. 3,, 1939.

J. M. RloRDANj WORM POLISHING MACHINE 6 Sheets-Sheet ,1

Filed Oct. 5', 1935 INVENTOR. J'ofin M Bio/Jazz Bx M -Q ATTORNEYS.

- Jn.3,1939. 1M RI D 2,142,415

WORM POLISHING MACHINE Filed Oct. 5, 1935 6 Sheets-Sheet 2 A TTORNEYS Jan. 3, 1939. RIORDAN 2,142,415

' WORM POLISHING MACHINE Filed Oct. 5, 1935 e Sheets-Sheet 5 76 E I 79 V. J 3,

O I I z I] O O 75' I I III a; 1 ,M ,f lea [I l m a m KP'5\6O .INVENTOR.

' ATTORNEYS.

1939- 1 J M. R |ORDAN 2,142,415

WORM POLISHING MACHINE I Filed Oct. 5, 1955 e Sheets-Shet 4 IINVENTOR. J'ofin M fiz'arakrz' ATTORNEYS.

Jan. 3, 1939. M, l RDA 2,142,415

WORM POLI SHING MACHI NE Filed-Oct. 5, 1935 6 Sheets-Sheet 6 la 2 4 /-9 I A9 E- E. INVENTOR.

J0]??? M fiiardazz A TTORNEYS.

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE WORM POLISHING MACHINE John M. Riordan, Detroit, Mich.

Application October 5, 1935, Serial No. 43,669

4 Claims.

This invention relates to gear polishing machines. More particularly, it relates to a machine which is adapted for polishing worm gears.

The specific embodiment of the invention illus- 5 trated in the drawings and described in the following specifications, is particularly adapted for the polishing of worm gear elements which are adapted for use in automobile steering gears.

Although it will be appreciated that the apparatus Ill and method described herein may find utility in polishing many and various kinds of worm gears, the specific machine disclosed herein relates to apparatus for polishing a particular kind of worm element. The form of worm element for which the machine described herein is particularly adaptable, is of the globoidal type and has a helical tooth structure which is of substantially constant pitch. This is contrasted to the conventional form of Hindley or hour glass type of worm gear, in which the tooth structure does not have a uniform pitch angle throughout its entire length. It will be appreciated that in the conventional globoidal type of worm gear, the increase in diameter of the gear element adjacent its ends necessitates a progressively decreasing pitch of the helix along which the teeth lie in order that these gears will properly mesh with a worm Wheel. As contrasted to this, the form of worm gears with which the present invention is primarily concerned, have a constant pitch angle irrespective of the diameter of the worm element.

It will be apparent that the Worm elements of the type described above, will not mesh with a conventional worm wheel and are adapted for use with a pivotally mounted member which engages merely a single tooth of the worm gear structure. It will likewise be apparent that due to the constant pitch of these gear elements, it is impossible to polish the surfaces of the gear teeth by lapping or by numerous of the other means conventional in the art.

The invention herein disclose-d comprises a polishing wheel which is mounted on a relatively fixed axis and has associated therewith a spindle which is at all times retained in a position inclined to the axis of rotation of the polishing wheel. This inclination is at such angle that it approximates the pitch of the helix of the thread on the worm element to be polished. It will be appreciated from the foregoing that inasmuch as the worm gears with which applicant is primarily concerned have a substantially constant pitch angle, irrespective of the diameter thereof, N that this inclination of the axis of the worm element to be polished, with respect to the axis of rotation of the polishing wheel, may be maintained substantially constant for polishing all of the teeth of the worm element. This spindle is preferably provided with means for adjustably 5 mounting a worm gear to be polished thereon and is itself mounted for rotation in a work table which is pivotally secured to the frame work of the machine, the axis of this pivot lying substantially in the plane of rotation of the polishing wheel. Means are provided for swinging the table, carrying this spindle, about its pivotal axis in an are such that the successive teeth on the worm element may be successively polished by the polishing wheel. Means are provided responsive to the movement of the work table for rotating the worm at a rate such that the polishing wheel will lie at all times in the channel between the two adjacent teeth of the worm element being polished.

It is a primary object of the present invention to provide a machine of this general type in which means are provided for accurately, delicately and resiliently urging the polishing wheel toward the work.

Yet another object of the present invention is to provide a mounting for the mechanism carrying the polishing tool which will provide a relatively friction-free movement of this mechanism in feeding the polishing wheel into the work.

Still further, the invention contemplates the provision of manual means for withdrawing the polishing mechanism from the work.

Still another object of the invention consists in novel mechanism for moving the work piece arcuately with respect to the polishing wheel, the work being moved on an arc of a circle whose center lies substantially in the plane of rotation of the polishing wheel, in order that all surfaces of the worm element may be machined in a single operation.

Yet another object of the invention consists in novel means for causing rotation of the worm element being polished, such rotation being synchronous with the movement of the work table past the periphery of the polishing wheel.

Yet another object of the present invention consists in the provision of mechanism for progressively varying the axis of rotation of the worm gear being polished, all positions of such axis lying, substantially tangential to the arc of a circle whose center lies in the plane of rotation of the polishing wheel.

Yet another object of the invention consists in the provision of novel drive mechanism embodyll ing a reciprocating member which serves to oscillate a quadrant which in turn causes a gradual rotation of the work table about its axis.

Still further, the invention contemplates the provision of interchangeable gears associated with this drive mechanism in order that the rate of movement of the work table through its arc may be accurately adjusted.

Still further, the invention contemplates the provision of a stationary arcuate rack which cooperates with a gear train on the work carriage in order that the movement of the work carriage will positively cause rotation of the work syne chronously with respect to the movement of the Work table.

Still further, the invention contemplates the provision of interchangeable gears in the gear train referred to in the preceding paragraph such that the relative speed of rotation of the work with respect to the movement of the work table may be accurately adjusted and determined.

Many other and further objects and advantages of the invention defined herein will be apparent from the following specification when taken in connection with the accompanying drawings forming a part thereof.

In the drawings:

Fig. 1 is a front perspective view of a complete machine embodying the features of the present invention.

Fig. 2 is a rear perspective View of the machine shown in Fig. 1.

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 1' showing the lower portion of the machine and the drive mechanism housed therein.

Fig. 4 is a top plan view of the machine showing the drive mechanism for the polishing element and the carriage supporting the work.

Fig. 5 is a fragmentary sectional view taken on the line 55 of Fig. 4 showing the means for urging the carriage, carrying the polishing element, toward the work and the means for retracting it from the work.

Fig. 6 is a sectional view taken on the line 66 of Fig. 4 showing the mounting of the work table and the drive mechanism for causing rotation of the work as the table is moved arcuately about its support.

Fig. 7 is a sectional view taken on the line 'I'1 of Fig. 4 showing the manner in which the polishing element is journalled in its carriage and the manner in which the carriage is supported on the housing or frame work of the machine.

Fig. 8 is a sectional view taken on the line 8-8 of Fig. 3 showing, in plan, the oscillatory drive mechanism for causing pivotal movement of the work table.

With more particular reference to the drawings, the specific embodiment of the invention illustrated therein comprises a main casing or housing I0 preferably formed of cast iron or other suitable material.

This casing has preferably formed on its upper surface a pair of track-way elements II which may, as shown in the drawings, be formed integrally with the casing. These track-way elements II serve to provide a runway for a carriage I2 which supports the polishing wheel as hereinafter described. A series of roller bearings I3 are mounted in the upper surface of the trackway I I in order that the sliding of the carriage I2 thereon will be relatively friction free. This, as will hereinafter be seen, is necessary in order to provide the accuracy and delicacy of feed necessary for the precise polishing of a worm element.

A spindle I6 is mounted transversely of the car riage I2 and is journalled in a pair of sets of roller bearings I1 and has secured to one extending end thereof a polishing wheel I8 mounted between a conventional pair of face plates I9.

As is seen by reference to Fig. 7 of the drawings, the inner of the two face plates I9 has a conical inner surface which fits tightly on a complemental conical end of the shaft I8 and the outer of the two face plates is threaded on the end of the shaft and locked in engagement to the inner plate by means of a set screw 20, the two face plates firmly retaining the polishing wheel I8 therebetween. The polishing wheel may be formed of any suitable material for producing a desired finish to the surfaces of the teeth of the element to be polished and preferably has its periphery formed of a configuration complemental to the channel existing between two adjacent teeth on the worm element to be polished. It has been found particularly desirable to use a polishing wheel formed of a resilient composition which is impregnated with abrasive material. Such a wheel has been found to be flexible and such flexibility will be seen to be particularly advantageous in apparatus of this general type.

The opposite end of the shaft I6 is provided with a pulley 22 adapted to receive a plurality of V-belts 23 which pass around this pulley and also pass around a pulley 24 secured to the shaft of an electric motor 25 which is also permanently mounted on the carriage I2. As is seen in Figs. 1 and 2, the pulleys 22 and 24 and interconnecting belts 23 may be covered by means of a suitable sheet metal housing 21 mounted on the carriage I2, and the major portion of the polishing wheel I8 may be likewise covered by protective jacket 28 secured also to the carriage I2. This enclosing housing 28 is preferably provided with an opening 29 in its forward side in order that the polishing wheel may engage the work, and preferably provided with an exhaust duct 30 for disposing of the particles of metal and dust resulting from the polishing action.

From the foregoing it will be seen that the carriage I2 is mounted for relatively friction free movement along the top of the casing and that the carriage has mounted thereon a polishing wheel and electric motor for driving the polishing wheel firmly secured to the carriage in order that these elements may be moved as a single unit.

In order to urge the polishing wheel against the work on which it operates, a cable 3I is secured to a suitable stud 32 on the underside of the carriage and passes forwardly over an idle pulley 33 mounted on the housing ID, and downwardly to a weight 34 suspended within the casing. It will be seen that the weight 34 serves normally to urge the carriage toward the work. An adjustable stop member comprising a set screw 35 journalled in a suitable bracket 36 mounted on the forward end of the frame, serves to limit the forward travel of the carriage I2 with respect to the casing. It will be seen that by rotation of the set screw 35, the forward travel of the carriage I2, and consequently the in-feeding of the cutting wheel toward the work may be very accurately and precisely adjusted.

From the foregoing it will be appreciated that the carriage is automatically urged into the work with a definite predetermined pressure which may be very delicately adjusted by varying the weight 34 supported on the cable 33.

Manual means are supplied for retracting the polishing wheel from the work. These means generally comprise the handle 38 which is permanently secured to a shaft 39 suitably journalled in bearings 40 in the walls of the casing I0. Secured to the shaft .39 internally of the casing and extending upwardly through a suitable slot 4| in the upper wall of the casing is a crank arm 42 which abuts against a vertically extending portion of the carriage I2. This crank arm 42 cooperates with the handle 38 to form a bell crank which, it will be seen, serves to provide manual means for retracting the carriage from the work. Exteriorily of the casing, a latch 43 is provided over which the handle 38 may be slipped in order to retain the carriage in retracted position.

Within the housing I0, automatic means are provided for positioning the work with respect to the polishing wheel I8. A motor is preferably mounted on the base of the casing I0 interiorly thereof and is directly connected to a change speed mechanism 5| for reducing the speed of the motor. The change speed mechanism, however, serves todrive a pulley 52 from which the rotational movement of the motor 50 is transmitted at a relatively reduced speed. A housing 55 is secured to one of the walls of the casing I0 by means of suitable bolts 56 and has journalled therein a substantially central, vertically disposed shaft 51, mounted at its upper end in a suitable series of roller bearings 58 and at its lower end in a similar series of roller bearings 59.- It is noted that the roller bearing assemblies 58 and 59 are so inclined to the aids of the shaft that they serve to absorb vertical thrust of the shaft to maintain it in substantially the proper vertical position. The shaft 51 is driven by means of a worm wheel 60 secured to the axial central portion thereof which meshes with a worm 6| secured to a transverse shaft 62 journalled in suitable bearings in the walls of the housing 55. One end of the shaft 62 carries a pulley 63 secured thereto, which is adapted to receive a belt 64 passing aroundthis pulley and also passing around the pulley 52 on the change speed mechanism attached to the motor. It will be seen from the foregoing that when the electric motor 50 is run, the change speed mechanism serves materially to reduce the speed of the drive from the motor and the worm gearing elements 6| and 60 serve to further reduce this speed in order to impart a relatively slow constant rotational movement to the vertically disposed shaft 51.

The upper end of the shaft 51 has preferably formed integrally therewith a crank shaft 85. This crank 65 is eccentrically disposed with respect to the shaft 51 and has journalled thereon a boss 66 which slides in guideways 61' in a transversely extending rocker arm 68. The rear end of this rocker arm 68 is pivotally connected to a. pair of links 69 by means of a suitable pivot pin 10. The opposite ends of the links 69 extend through a suitable aperture in the wall of the casing I0 and have their inner ends pivoted on a suitable fixed stud 1| These links 69, as will be seen, serve to prevent any material transverse movement of the rear end of the rocker arm 68, but permit a limited longitudinal movement of this arm with respect to the fixed stud II, the purpose of which will hereinafter be clearly seen.

The opposite end of the rocker arm 68 has a quadrant section 15 pivotally connected thereto by means of pivot pin 16. This quadrant section I5 is, itself, mounted for pivotal movement on a stub shaft 11, journalled in a suitable bearing I8 in a housing 19 secured to the casing I0. The quadrant section I5 is provided with an arcuate series of teeth which are arranged concentrically with respect to the axis of the stub shaft 11, and it will be seen that as the shaft 51 is rotated, the eccentric shaft 65 will impart a rocking movement to the longitudinally disposed rocker shaft 68, and consequently cause a pivotal movement of the quadrant section about its stub shaft TI.

A work table is provided and is adapted for pivotal mounting on the casing I0. This work table is preferably mounted on a vertically dis-. posed shaft 8| which is journalled for rotation in a housing 82 preferably formed integrally of the casing I0. The shaft 8| is mounted in suitable roller bearings 83, which serve to maintain the shaft in predetermined vertical position, and has secured to its lower end a spur gear 84 which is adapted to engage the teeth 80 on the quadrant section 15. The shaft 8| has a laterally projecting arm 85 which has journalled in its outer end a shaft 86 mounted for rotation therein by means of suitable bearings 81. It will be seen that this arm 85 and the shaft at its outer end will follow an arcuate path as the shaft 8| is driven through partial rotation by means of the quadrant section 15. The lower end of the shaft 86 has a spur gear 88 secured thereto, which meshes with a rack 89 secured in a supporting bracket 90 which is in turn bolted to the wall of the casing I0.

The upper end of the shaft 86 has secured thereto a gear 93 which meshes with a gear 94 journalled in the outer end of the arm 85. The shaft of the gear 94 is connected by means of a suitable universal joint 96 to an upwardly extending shaft 91, which has its upper end connected to a second universal joint 98. The opposite side of the universal joint 98 is connected to a shaft 99 which, as will be hereinafter seen, serves to drive the work.

A bracket I00 is secured to the upper end of the shaft 8| and constitutes a work table. The work table I00 has an upstanding portion IOI which has an outwardly presented, vertically disposed flat face. The face of this upstanding portion |0I has a longitudinally disposed keyway therein which serves to receive a key I02. A bracket I03 is secured by means of suitable bolts I04 to the flat upstanding face IN and, likewise, has a keyway therein which is also adapted to receive the key I02. The bracket I03 is preferably provided with relatively long longitudinally disposed slots through which the securing bolts I04 pass in order that it may be adjusted longitudinally with respect to the work table I00, the key I02 serving to retain the bracket in relatively fixed vertical position with respect to the work table. It will be appreciated that this construction provides a relatively rigid mounting for the bracket I03 with respect to the work table.

Preferably, formed integrally with the bracket I03 is a housing I05 which serves to enclose and provide bearings for the shaft 99 described above. The housing I05 also is provided with an upper transversely extending cylindrical portion which A spindle I09 has a tapered shank which is adapted to fit tightly within a conical recess axially of the spindle receiving shaft I06. This spindle is secured in position by means of a draw shaft H0 which has a shoulder III on its outer end and an extending portion II2 adapted to be engaged by a wrench. The shoulder III serves to engage on one side the extreme outer end of the spindle receiving shaft I08 and on its other side engages the inside shoulder of a collar H3, which is threadably secured to the outer end of the spindle receiving shaft. The inner end of the draw shaft I I0 is threadably secured coaxially with the spindle I09 and it will be seen that the rotation of the draw shaft IIO will serve to draw the spindle I09 into the spindle receiving shaft and cause a tight engagement of the tapered portion of the spindle with the tapered recess in the spindle receiving shaft. It will likewise be apparent that when the draw shaft H0 is rotated in the opposite direction, it will tend to force the spindle outwardly from the spindle receiving shaft and disengage this tight tapered fit. The outer end of the spindle I09 is provided with means for receiving a globoidal worm gear to be polished. This worm gear shown as I I5 is mounted coaxially of the spindle I09 and has one end adapted to engage a collar H6 which is secured accurately in position on the spindle I09 by means of a lock nut Ill. The worm element is forced tightly into the collar I I6 and locked in position by means of a suitable nut II8 threaded on the outer end of the spindle.

From the foregoing, it will be seen that as the work table I00, together with the shaft 8i on which it is mounted, is swung about its axis, the arcuate movement of the arm 85 formed integrally with its shaft 8| will cause an arcuate movement of the shaft 86 journalled in this arm. The arcuate movement of the shaft 86 will cause a rotation of this shaft due to the engagement of the gear 88 thereon with the stationary arcuate rack 89. This rotation of the shaft 86 will cause rotation of the intermeshing gears 94 and 93 and the consequent rotation of the upwardly extending shaft 91, which through the universal joint 98 serves to drive the shaft 99. As has been explained above, this shaft 99, by means of the intermeshing gears I91 and I08, causes a rotation of the spindle receiving shaft I 06 and produces a consequent rotation of the work. From the above, it will be apparent that the rotation of the worm element to be polished will be synchronous with the movement of the work table about its axis. It will be likewise apparent that by substituting gears having slightly different ratio for the gears 93 and 94, the ratio of rotation of the spindle to the rotational movement of the work table as a whole may be varied as may be found desirable.

It is further apparent that the axis of the rotation of the work table about the shaft 8 I, lies in the same plane as the polishing wheel I8. Likewise, it will be clear by reference to Fig. 6 of the drawings, that the axial central portion of the worm element to be polished lies substantially in the same plane as the axis of the work table. Consequently, it will be apparent that as the work table is swung about its axis, the worm element to be polished will be moved arcuately about the peripheral edge of the polishing wheel on an arc of a predetermined base circle. It will be apparent that the radius of this predetermined base circle may be accurately adjusted by the adjustable mounting of the bracket I03 on the vertically extending portion I 0| of the work table. While the machine is in operation, the motor 25 serving to drive the polishing wheel, is preferably run constantly. However, the motor 50 located interiorly of the casing I0, which serves to control the movement of the work around the polishing wheel, is preferably controlled by the following means: A switch I20 is preferably secured to the outer side wall of the casing ID in such a position that it will be engaged by the handle 38 when it is in its downward position. This switch I20 when closed by the engagement of the handle 38 therewith, serves to start the electric motor 50. A switch I2I is located adjacent the terminal end of the arcuate rack 89 in order that, as the work table is swung through its entire arc, an outwardly projecting arm I22 secured to the work table, will engage the switch I2I to cut off the motor and discontinue operation of the machine.

In polishing a worm element, such as the element II5 indicated in the drawings, the worm element is first firmly locked in position on the spindle I06. The polishing wheel carriage is held in retracted position by means of the actuating arm 38 being hooked over the latch 43. The work table is in position with the gear 88 at the end of the rack 89 with the arm I22 in contact with the switch I2I. It will be apparent that, as the work table is in this position, the extreme outer end to the worm element to be polished will be substantially in the plane of the polishing wheel. The handle 38 is then slipped off the latch 43 and lowered into contact with the switch I20. This lowering of the handle 38 permits the polishing wheel carriage I2, urged by the weight 34, to move forwardly until the forward edge of the polishing wheel engages the groove between two adjacent teeth of the worm element to be polished substantially at the end of this groove. The polishing action will then begin. It will be seen that, as the handle 38 is lowered into contact with the switch I20, the motor 50 in the casing of the machine will begin to run, which will produce a slow rotational movement of the shaft 51. This rotational movement of the shaft 51 through the rocker arm 88 will cause a gradual arcuate reciprocation of the quadrant section 15 about its pivot which will in turn cause a gradual rotational movement of the work table. As has been seen, movement of the work table about its pivot will swing the element being polished, arcuately past the peripheral edge of the polishing wheel. It will be apparent that, as this rotational movement of the work table takes place, the engagement of the gear 88 with the rack 89 will cause a slow rotational movement of the worm about its own axis in a direction opposite to the direction of rotation of the polishing wheel. The gears causing this drive have such a ratio that the worm element being polished will be rotated at a speed such that the polishing wheel will be maintained in the groove between two adjacent teeth of the worm element and that the worm element as a whole will be arcuately moved and threaded past the peripheral edge of the polishing wheel. It will be apparent that when the gear 88 reaches the end of the rack 89 the work table will, by action of the rocker arm and quadrant section, be swung in the opposite direction, and the worm element will now be rotated in the opposite direction. The worm will be threaded past the peripheral edge of the polishing wheel in the opposite direction and will have a final finish imparted thereto. It will be apparent that after the work table has been moved through its complete are, 15

the arm I22 will come into engagement with the switch lZl shutting ofi the motor 50 and discontinuing the drive of the work table.

From the foregoing, it will be seen that as the polishing wheel engages the work in the first half of its cycle of movement, the relative rotation of these members will be in opposite directions to smooth the surfaces of the tooth structure and during the last half of the cycle they will be rotating in the same direction to impart a final polish.

From the foregoing, it will be clear that the specific embodiment of the invention described in the foregoing and illustrated in the accompanying drawings, is merely illustrative of one form of the invention and that the inventive concept disclosed herein is susceptible of many other and further modifications falling within the scope of the subjoined claims.

What is claimed is:

l. A machine for polishing worm wheels of the hour-glass type including in combination, a supporting base, a relatively flexible polishing wheel mounted for rotation on said supporting base, a work supporting table pivotally connected to said supporting base and having the pivotal axis thereof lying in the plane of said polishing wheel, a work supporting spindle rotatably mounted on said table whereby pivotal movement of said table will serve to move a work piece carried by said spindle arcuately past the periphery of said polishing wheel, means for resiliently urging said polishing wheel into engagement with the work piece carried by said spindle, motor driven means on said supporting base for causing pivotal movement of said work supporting table about its axis and means responsive to such pivotal movement for effecting synchronous rotation of said spindle with respect to movement of said work supporting table.

2. A machine for polishing worm wheels of the hour-glass type including in combination, a supporting housing, a polishing wheel mounted for rotation on said housing, a work supporting table pivotally connected to said housing, a work supporting spindle rotatably mounted upon said table whereby pivotal movement of said table serves to move a work piece carried by said spindle arcuately past the periphery of said polishing wheel, means for resiliently urging said polishing wheel into engagement with the work piece carried by said spindle, an arcuate gear segment carried by said supporting housing and a gear train interconnecting said work supporting spindle with said gear segment whereby pivotal movement of said work supporting table will cause a synchronous rotation of said spindle with respect thereto.

3. A machine for polishing worm wheels of the hour-glass type including a supporting housing, a polishing wheel mounted for rotation on said housing, a work supporting table pivotally connected to said housing and having the axis thereof lying in the plane of said polishing wheel, a work supporting spindle adapted to receive and mount a worm to be polished, said work supporting spindle being inclined to the plane of said polishing wheel at an angle susbtantially equal to the helix angle of said worm, means for resiliently urging said polishing wheel into engagement with the work piece carried by said spindle, and means for causing pivotal movement of said work supporting table to move the same past the periphery of said polishing wheel.

4. A machine for polishing worms of the hour glass type including in combination, a supporting housing, a polishing wheel mounted for rotation on said housing, a work supporting table pivotally connected to said housing, a spindle support adjustably mounted on said work table, a spindle adapted to carry a worm to be polished mounted for rotation in said spindle support whereby said work table serves to move said worm to be polished areuately past the periphery of said polishing wheel, motor driven means on said supporting base for causing pivotal movement of said work supporting table about its axis, an arcuate gear segment carried by said supporting housing, a universally jointed shafting mounted for rotation in said work table, said shafting carrying at one end a gear adapted to mesh with said segment and at the other end a gear serving to drive said spindle whereby pivotal movement of said work table serves to eiTect synchronous rotation of said work carrying spindle.

JOHN M. RIORDAN.

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