US1622628A - Worm-grinding machine - Google Patents

Description

a ch 9 7 H. E. DURKEE WQRM GRINDING MACHINE 7 Sheets-Sheet 1 Filed March 28, 1925 I TTORNEY March 29', 1927. H. E. DURKEE WORM GRINDING MACHINE 7 Sheets-Sheet 2 Filed March 28, 1925 A TTORIIEY v March 1927' H. E. DURKEE WORM GRINDING MACHINE Filed March 28 1925 7 Sheets-Sheet 5 INVENTOR H 6.19MB

A TTORIVEY H. E. DURKEE WORM GRINDING MACHINE March 29, 1927. 1,622,628

Filed March 28. 1925 '7 Sheets-Sheet 4 INVENTUHI 2 1 March- 927 H. E. DURKEE WORM GRINDING MACHINE Filed March 28, 1925 7 Sheets-Sheet 5 WWW ,4 TTORNEY -l|| I.. Illlll l l l I I l l v I ll March 29, 1927. E. DURKEE worm enmnme MACHINE Filed March 2 ,1925 '7 Sheets-Sheet 6 INVEIITUR l TTURIIEY March 29 1927.

E. LJURKEE WORM GRINDING MACHINE Filed March 28, 1925 7 Sheets-Sheet H's/Mignon BY 4 412 ara/Mn Patented Mar. 29, 192.7. I v V UNITED STATES PATENT OFFICE.

HENRY E. DURKEE, F GLASTONBUBY, CONNECTICUT, ASSIGNOR TO PRATT & WHIT- NEY COMPANY, OF NEW YORIL N. Y., A CORPORATION OF NEW JERSEY.

WORM-GRINDING MACHIN E.

Application filed March 28.19211. Serial No. 19,094.

This invention relates to grinding ma chines and particularly to' a machine for grinding the helicoidal surfaces of screw. threads on Worms or other threaded members. More especially the machine is def signed for grinding steering worms designed for use on automobiles or other motor driven vehicles. I

An object of the present invention is to provide a machine designed for rapidly grinding steering worms upon both flanks ot\ their screw threaded portions so that these surfaces may, after the worm has been hardened, be generated to a high precision.

Another object of the invention is to provide cam means to reciprocate the table or support carrying the worm being groundpast the abrasive wheel while it is being rotated continuously in one direction, the

rotary movement taking place in timed relation to the reciprocatory movements of the work supporting member.

Another object of the invention is to provide a main shaft-rotating in one direction at constant speed during operation and hav-. ing driving means for rotating a work carrying spindle at any predetermined rotative speed relative thereto, and to provide driving means operating through the-work spindle for a main cam drum adapted to reciprocate the table or work supporting member;

Another object. of the invention is to provide a grinding machine having simple means for indexing the work spindle permitting multiple start worms to be readily ground in a continuous operation, these means preferably being controlled by timing the rotative movement of the spindle relative to the reciprocatory movement of the support and work, so that first'one of the threads will be ground and then the next and so forth.

Another object of the invention is to provide cam actuated means to advance and withdraw the wheel and wheel head relative to the worm being ground so that it may contact with the work while the table or support is moving in one directiori and will be entirely disengaged therefrom during movement of the support in the opposite direction.

A still'further object of the invention is i to provide a wheel head angularly adjustable and having a shaft thereon parallel to the wheel spindle adapted to be driven through bevel gears andadapted, by means of a belt, to rapidly. rotate the Wheel spindle.

lVith these and other objects'in vlew, my

invention consists in the features of construction and operation set forth in the followingspecification and illustrated in the accompanying drawings.

In the accompanying drawings annexed hereto and forming a part of this specification, I have shown my, invention embodied 1n a grinding machine for automobile steering worms, but it will be understood that the invention can be otherwise embodied and that the drawings are not to be construed as defining or limiting the scope of the invention, the claims appended to this specification being relied upon for that purpose.

In'the drawings:

Figure 1 is a front elevation of the complete machine.

' Fig. 2 is a transverse sectional view in elevation taken substantially upon line 2-2 of Fig. 1.

Fig. 3 is a sectional view in elevation showing the table reciprocating cam and rotating means for the work driver.

Fig. 4 is a horizontal sectional view of the work driver and adjacent parts.

Fig. 5 is a sectional view of the main'cam and work rotating means taken upon line 5-5 of Fig. 3.

F ig. 6 is a horizontal view partly in section of the wheel head and the wheel rotating mechanism. I

Fig. 7 is a front elevation of the actuating means for the work rotating and wheel advancing mechanisms.

Fig. 8 is a sectional view in elevation taken upon line 66 of Fig. 7.

.Fig. 9 is a detail of the actuating means forftlie wheel advancing and withdrawing mechanism.

1 Fig. 10 is a detail of the pawl and memberon which it is mounted forming partof the wheel advancing and withdrawing mecha- IllSIIl.

Fig. 1 1 is a detail view of the" wheel ad'- vancing' and withdrawing cam and levers head.

Fig. 12 is. a front elevation of the wheelfeeding mechanism, the hand wheel being broken away. 1

or table slidable thereon ;.third, a wheel head movable in a direction at right angles to the work supporting table and having an angularly adjustable rotatable abrasive wheel; fourth, cam means to reciprocate the table; fifth, continuous rotating means for a work driver or spindle-on the work support on which a worm being ground may be mounted; sixth, means adapted to reciprocate the support in timed relation to the rotations of the work driver; seventh, cam

means to advance and" withdraw the wheel and wheel head relative to the worm being ground-in timed relation to the reciprocations of the supporting means; and eighth, means to feed the wheel relative to the worm being ground at predetermined intervals during the cycle of operations of the machine.

Referring more in particular to the figures of. the drawings, I provide a base 10 having a table or work supporting means 11 thereon adapted to slide longitudinally of the base 10 upon suitable ways 12 and 13. In rear of the table 11 and adapted to slide upon ways 14 extending at right angles to the ways 12 and '13 for the table 11 is a wheel head 15 on which is adjustably mounted an abrasive wheel 16. .The means for driving and positioning the wheel 16 will presently be more fully described. On the table 11 are mounted work supporting and rotating means. These, in the embodiment of the invention illustrated, comprise a fit headstock 17 provided with a fixed center 18 and work driving member 19 and a tailstock 20 having a center spindle 21 in alignment with the headstock center 18. The worm W being ground may therefore be supported upon a fixed axis and will be reciprocated by the sliding movements of the table 11 and rotated with the driver 19.

Preferably the supporting table 11 on it's under side is provided with a longitudinally extending shaft 22 rotatably mounted -in suitable bearings and held from end-wise movement relative to the table 11. This shaft 22 is adapted to be constantly rotated at any desired speed during operation through driving connections from a main driving shaft 23. The driving connections between shafts 23 and 22 comprise gears 24 some of which may be changed to vary the rotative speed of the shaft 22 relative to shaft 23. A spiral gear 25 splined to the shaft 22, so that it remains in fixed position during reciprocations of the table 11, is provided which meshes with one of the driving gears 24. On this shaft 22 also is a gear 26 in mesh with an idler 27 supported upon the table 11 which in turn is in mesh with a gear 28 on the work supporting and driving member 19. From Fig. 3 it will be clearly seen that the driving gear 28 is mounted upon a sleeve 29 surrounding the spindle 30, this sleeve 29 having a driving dog 31 outstanding therefrom for engagement with a dog on the worm W being ground. The spindle 30, which may be nonrotatable, isprovided with the center 18 upon which one end ofthe work being ground may be mounted.

Adjacent the gear 28 for rotating the driver 19 is another gear 32 adapted to mesh with a gear 33 on an intermediate driving shaft 34. This driving shaft 34 through geared connections is adapted to rotate a main cam drum 35 for reciprocating the table 11. The driving connections for this cam drum 35 are very clearly shown in Figs. 3, 4 and 5. Preferably, and as shown in Figs. 3 and 4 a differential driving mechanism 36 is interposed in the drive for the cam 35 so that the rotative position of the cam 35 may be manually varied relative to that of the driver 19 during operation. This differential comprises a rotatable memher or housing 36 which may be rotated by a worm 37 engaging a worm wheel 38 cut into its periphery. The worm 37 as shown in Fig. 5 is on a short forwardly extending shaft 39 having a hand wheel 40 on its forward end. Rotation therefore of the hand wheel 40 will rotate the housing 36 and parts enclosed therein.

Within this housing 36 is an intermediate shaft 41 having a compound gear 42 thereon, one member of this compound gear engages a gear 43 on .the shaft 34 and the other member with another gear 44 on a second intermediate driving shaft 45. This last intermediate driving shaft 45 is provided with a gear 46 at its outer end adapted to mesh with an idler gear 47 in mesh with a gear 48 on the shaft carrying the main cam drum 35. Preferably these last mentioned gears 46, 47 and 48 are mounted so that they may be readily changed enabling the cam drum 45 to be driven at any predetermined rotative speed relative to that of the work rotating member 19. It will be seen too that the cam drum 35 will be rotated always in the same direction from and in timed relation to the rotation of the work supporting and rotating member 19.

The main cam drum 35 is provided with a peripheral groove 48 of generally heli- IIH eoidal form which is adapted to be engaged by a roller 49. The mounting for this cam engaging roller 49 is clearly shown in Fig. and preferably comprises a short shaft 50 suitably mounted upon ball bearings and fixed permanently in position in the base 10. It will be seen therefore that rotation of the cam drum 35 will reciprocate the table 11 and head and tailstocks 17 and 20 back and forth enabling the work W being ground to be traversed axially simultaneously with its rotative movement. By means of the housing 36 the cam drum may be rotated relative to the work driver 19. Rotating the worm 37 by the hand wheel 40 rotates the housing 36 and the compound gear 42 mounted therein. This therefore rotates the intermediate driving shaft 45 and therefore the cam drum 35. Normally during operation the housing 36 is stationary but can be rotated at any time to vary the rotative position of the cam drum 35 relative to the work W and thus vary the relative axial positions of the work W and the wheel 16 to fjustify the threads with the abrasive wheel,

The wheel support 15 comprises a body member 52 adapted to slide upon the ways 14 provided in the top surface of the base If). these as stated above extend in a direction normal to those upon which the table 11 slides. This body member 52 is provided with an opening in which a sleeve 53 is mounted so that the sleeve may be angularly adjusted. A flange 53 on the forward portion of this sleeve 53 enables it to be fastened directly to the body member 52 of the support 15 in any rotative position of the sleeve. Also upon the forward end surface of the sleeve 53 a wheel head 54 is mounted within which a wheel carr ing spindle 55 is rotatably mounted. lhis spindle 55, as shown in Fig. 6, is provided with a pulley 56 for driving it and with the abrasive wheel 16 mounted adjacent one end.

In rear of the sleeve 53 and suitably fastened thereto so that it-may be angularly adjusted with the sleeve, isan annular member 57 carrying bearings for a transverse shaft 58, This shaft 58 is provided with a pulley 59 for a belt 60 adapted to pass over and drive the pulley 56 on the wheel spindle 55. At an intermediate point on this transverse shaft 58 is a bevel gear 61 keyed thereto and adapted to mesh with a corresponding bevel gear 62 on the forward end of a rearwardly extending shaft 63. A pulley 64 on this rearwardly extending shaft 63 provides means for rotating it from the main driving shaft 23. Preferably and as shown in Fig. 2, this rearwardly extending shaft 63 ma be carried in a separate member boltec directly to the body member 52 of the wheel support 15. It will be seen from the above described parts that By means of the angularly adjustable head 54 on which the wheel spindle 55 and wheel 16-are mounted, the wheel spindle 55 may be angularly adjusted to properly engage the worm W being ground. In

making angular adjustments of the wheel spindle 55, no interruption to the drlving means for the wheel 16 takes place and no ad ustments of the driving constructions are necessary.

In order to advance and withdraw the wheel slide 15 and wheel 16 into and out of operative position, a nut 60 is mounted on the lower surface of the wheel supporting slide 15 adapted to be engaged by a screw 61 rotatably mounted and axially movable within the base 10. These are shown clearly in Fig. 2. This screw 61 is provided with opposed collars 62 between which a yoke member 63 may be disposed adapted to be engaged by a lever 64 pivotally mounted upon a stud 65 within the base 10. Oscillation of this lever 64 by means of a pull rod 66 enables the screw 61 to be bodily moved forwardly or rearwardly of the machine and thus move the wheel 16 and attached parts. The means for oscillating the lever 64 to advance and withdraw the wheel 16 during operation will presently be described.

In order to adjust the position of the wheel 16. toward or from the work being ground for feeding during operation or for adjusting for different diameters of worms, means are provided to rotate the screw 61. For this purpose a gear 67 is provided on the forward end of the screw 61 adapted to mesh with an elongated pinion 68 so that the gear 67 Will always be in mesh with its pinion 68 in all positions ofthe lever 64 and screw 61. By means of a shaft 69 on which this pinion 68 is carried, and which extends adjacent the forward vertical surface of the base 10, the screw 61 may be rotated stepby step either manually or automatically by the reciprocatory movements of the table 11. Preferably the pinion shaft- 69 at its forward end is rovided with a gear 70 in mesh with a gear 71 on a short shaft 7 2 extending to the front of the machine. On the forward end of this short shaft 72 are mounted the hand wheel 73 for manually adjusting the position of the wheel 16 and the ratchet wheel 74 for feeding it either manually or automatically. These means for rotating the shaft- 72 are more clearly shown in Figs. 12 and 13. On the forward end of this short shaft 72 1s a .large ratchet wheel 74 adapted to be engaged by a pawl 75 pivot-ally mounted on a hand lever 76. Oscillation of this hand lever 76 will therefore rotate the ratchet wheel 74 slightly and therefore rotate the screw 61 through a very small angle. Preferably, movement of the hand lever 76 is limited by an extension 7 7 formed integrally on the lever 76 engaging an adjustable stop 78 oi'itstanding from the base 10. 78, as shown in Figs. 12 and 13, comprlses a small screw, the forward end of which is adapted to be engaged by the extension 77. In order to feed the wheel 16 automatically during operation of the machine, a bell crank 80 is pivotally mounted upon the base 10, one arm of which is provided with a roller 81 adapted to be engaged by dogs 82 adjustably positioned on the front surface of the table 11. Engagement of the bell crank 80 with one or the other of these dogs 32 oscillates it and thus oscillates the extension 77 bymeans of a rod 83 attached to the other arm of the bell crank 80 and engaging the extension 77 on the lever 76. Preferably, a spring 84 is adapted to be compressed by movement of these means in one direction and the bell crank 80 and pawl 7 5 are held in their retracted positions by spring 84 which surrounds an extended por-' tion of the rod 83.

The main driving shaft for the machine above referred to comprises a forwardly extending shaft 23 rotatably mounted Within the base 10 and having a driving pulley 90 near its rear end. Adjacent the main driving pulley 90 is the pulley 67 for driving the wheel 16 over which operates the belt 66 passing over the pulley 64 on the wheel support 15. On the extreme forward end of shaft 23 is a gear 91 adapted to mesh with the first of the train of gears 24 for rotating the shaft 22. The last gear of the train 24 drives a spiral gear on the shaft 22 below the work supporting table 11 as has been above described. By these means the work W may be rotated at various speeds and the cam dr'um also rotated to vary the speed of reciprocation of the table 11.

Also on the main driving shaft23 at an intermediate point is driving gear 92 which, through a compound gear 93, drives agear 94 on a constantly rotating cam shaft 95 for actuating the wheel withdrawing and advancing mechanism. Preferably on the main driving shaft 23 is a clutch 96 so that the forward section of the driving shaft on which are mounted the gears 91 and 92 may be stopped or started independently of the part carrying the pulleys 90 and 67. This clutch is shown in Figs. 2 and 8 and may be act Hated by a lever 97 connected to a yoke This stop 98 engaging a movable member on the clutch.

The driven gear 94 is preferably mounted on a sleeve 99 formed integrally with a ratchet wheel 100 which is therefore constantly rotated with the driving shaft 23.

and ear 9.4 are rotatably mounted carries a mem r 102 on which .a pawl 103 is pivotally mounted. TlilS pawl 103 is'adapted to be engaged or disengaged relative to the ratchet wheel 100 by means presentlly to be described. Rotation of the gear 94 ant shaft 101 when the pawl 103 is in engagement with the ratchet wheel 100 rotates acam drum 104. A roller 105 on a pivoted arm 106 engages a peripheral groove 107 on this cam drum 104 so that rotation ofthe drum 104 oscillates the arm 106; Preferably the arm 106 is mounted on an oscillating shaft 108, this shaft 108'also having an upwardly extending arm 109. At the upper end of the arm 109 is attached the pull rod 66 for moving the wheel support 15 to control the movements of the wheel 16 into-and out of engagementwith the work being ground.

The shape-70f the groove 107 in the cam drum 104 is such that approximately onehalf a revolution will oscillate the pivoted arm 106 from one extreme position to the other. Preferably a counterweight 110 is supported within the base 10, its supporting cable 111 passing over an idler and being attached to a part of the wheel supporting slide 15. This weight 110 normally holds the wheel slide 15 as far forward as possible and assists the cam 104 in advancing the wheel 16 toward the work and retaining it positively in that position during grinding.

To control the rotative movement of the cam drum 104 means are provided to control the position of the pawl 103 so that it may be withdrawn from operative relation with the ratchet wheel 100 at predetermined positions or allowed to engage therewith and therefore rotate the shaft 101 and cam 104. The pawl 103 carried by its member 102 is normally oscillated to its engaging position by a spring 112 shown in Fig. 10. Adapted to engage a rearward extension of the pawl 103 are levers 114 pivotally mounted so that they may be moved into or out of engaging position. Means are provided so that when one lever 114 is moved to disengaging position, the other one remains in a position where it will be engaged by the pawl 103 upon approximately onehalf a revolution of the member 102. As shown in Fig. 7 the levers 114 contacting with the pawl 103 are mounted on short shafts 115 which have fastened to their forward ends levers 116 adapted to be engaged and oscillated by a central lever 117 pivotally mounted at its upper end and dis- 'A shaft 101 on whichthe ratchet wheel 100 p oscillate this central lever 117 it is miide of bell-crank form, as will be seen in Fig. 1,

the opposite arm of which is attached to a rod 11.8. The opposite end of the rod 118 is fastened to a lever 119 adapted to be engaged and oscillated by adjustable dogs 120 on the table 11.

Contact of the lever .119 with one of the dogs 120 oscillates one of the pawl engaging levers 114 so that it is moved to its disengaged ratchet wheel 100 by the opposite lever 11.4.. .The cam drum 104 is then held from rotation until, by reason of the movement of the table 11 in the opposite'direction, the lever 119 is engaged andoscillated in the opposite direction by the opposite dog 120. This disengages the opposite member 114 from the pawl 103 thus enabling it to engage a ratchet tool on wheel 100 and rotate the cam drum 104 another fraction of a turn when the pawl 103 engages the first lever 114 and is again disengaged. Thus, by engagement of the lever 119 with the dogs 120 alternately near the ends of the table movement in each direction, the wheel 10 is advanced or withdrawn from the work. By attaching the rod 118 to one or the other arms of the dog engaging lever 119 the advancing movement of the wheel 10 takes )lace at either end of the table movement. lhe grinding operation may therefore take place while the table 11 is moving in either direction.

What- I claim is:

1. A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, an angularly adjustable wheel head movable toward and from the su )porting means and having a rotatable abrasive wheel therein, a constantly rotatingshaft, a cam thereon for reciprocating the work supporting means, and means for rotating the work simultaneously with the reciprocatory movements of the work supporting means.

2. A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel headadjustable toward and from the work supporting meansand having a rotatable abrasive wheel therein, a constantly rotating shaft, a cam driven by said shaft for reciprocating the work supporting means, and means for rotating the work simultaneously with and in timed relation to the reciprocatory movements of the work supporting means,

A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head adjustable toward and from the work supporting means and having a rotatable abrasive wheel therein, a constantly rotating shaft, a "am driven by said shaft for reciprocating the work supporting means, and means also operated by said shaft for rotating the work simultaneously with and in' timed relation to the reciprocatory movements of the work supporting means. i

4. A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head adjustable toward and from the work supporting means and having a rotatable abrasive wheel therein, a constantly rotating shaft mounted on and movable with the supporting means, a cam driven by said shaft for reclprocating the work supporting means, and means operated by said shaft for rotating the work simultaneously with and in timed relation to the reciprocatory movements of the work supporting means.

A worm grinding machine con'lprising in combination, a base, work supporting means slidably mounted thereon, a wheel head adjustable toward and from the work supporting means and having a rotatable abrasive wheel therein, a constantly rotating shaft, means operated by said shaft for rotating the work, acam driven by the work rotating means for reciprocating the work supporting means whereby the reciprocatory movements of the work supporting means take place simultaneously and in timed relation with the rotation of the work and means to vary the rotative movement of the work supporting means relative to its reciprocatory movement.

(3. A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head adjustable toward and from the work supporting means and having a rotatable abrasive wheel therein, cam means toreciprocate'the work supporting means past the wheel, means to rotate the work simultaneously with and in timed relation to its reciprocations, means to advance and withdraw vthe wheel in timed relation to the reciprocatory and rotary movements of the work supporting means. and means to vary the rotative movement of the work supporting means relative to its reciproeatory 1n0vement.

7. A. worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head having a rotatable abrasive wheel therein, cam means rotatably mounted on said supporting means to reciprocate the work supporting means past the Wheel, meansto rotate the work in timed relation to its reciproeations, and means to advance and withdraw the wheel in timed relation to the reciprocatory movements of the work supporting means.

8. A worm grinding machine compris ng in combination, a base, work supportlng means slidably mounted thereon. a wheel head having a rotatable abrasive wheel therein, cam means to reciprocate the work supporting means past the wheel, means to advance and withdraw the wheel, and means to continuously rotate the work in the same direction during the reciprocatory movements of the work supporting means.

5). A worm grinding machine comprising in combination. a base. work supportin g means slidably mounted thereon, a wheel head .having a rotatable abrasive wheel therein. cam means to reciprocate the work supporting means past the wheel. means to advance and withdraw the wheel, means to continuously rotate the work during the reciprocatory movements of the work supporting means, 'and means to vary the rotative and reciprocatory movements.

10. A worm grinding machine comprising in combination, a base. work supporting means slidably'mounted thereon. a wheel head having a rotatable abrasive wheel therein. cam means to reciprocate the work supporting means past the wheel, means to advance and withdraw the wheel, and means to continuously rotate the work during the reciproeatory movements of the work supp rting means, said cam means being rolated by said work rotating means and in timed relation thereto.

l1. worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head having a rotatable abrasive wheel therein, cam means mounted on said work supporting means to reciprocate the work supporting means past the wheel, means to advance and Withdraw the wheel, and means to continuously rotate the work during the reeiprocatory movements of the work supporting means.

12. A worm grinding machine comprising in combination, a base, work supporting means slidable thereon, work rotating means on said supporting means, a cam shaft rotatably mounted on said supporting means, driving means for said work rotating means, a peripheral cam on said shaft adapted to engage a fixed member on said base whereby rotation of said shaft will recipro- (ate said supporting means, and gear means driven from said work spindle to rotate the cam shaft in timed relation to the rotation of the work.

13. A worm grinding machine comprising in combination, a base, work supporting means slidable thereon, work rotating means on said supporting means, a cam shaft rotatably mounted on said supporting means and slidable therewith, driving means for said work rotating means, a peripheral cam on said shaft adapted to engage a fixed memher on the base whereby rotation of said shaft will reciprocate said supporting means, means to rotate the work at predetermined variable speeds, and means driven from said work spindle to rotate the cam shaft.

14:. A worm grinding machine comprising in combination, a base, work supporting means slidable thereon, work rotating means on said supporting means, a cam shaft rotatably mounted on said supporting means and slidable therewith, driving means for said work rotating means, a peripheral cam on said shaft adapted to engage a fixed memher on the base whereby rotation of said shaft will reciprocate said supporting means, means to rotate the work at predetermined variable speeds, means driven from said work spindle to rotate the cam shaftin timed relation thereto, and means to vary said last named means.

15. A worm grinding machine comprising in combination, a base, work supporting means slidably mounted thereon, a wheel head having a rotatable abrasive wheel therein, a cam for reciprocating the work supporting means, means for rotating the work simultaneously with the reciprocatory movements of the work supporting means, and means for manually varying the angular positions of'said cam and work rotating means.

1677i worm grinding machine comprising in combination, a base. .work supporting means slidably mounted thereon, a wheel head having a rotatable abrasive wheel therein, a cam for reciprocating the work supporting means. means for rotating the work simultaneously with the reciprocatory movements of the work supporting means, and a differential driving mechanism disposed between said work rotating and support reciprocating means.

17. A worm grinding machine comprising in combination, a base. work supporting means slidably mounted thereon. a wheel head having a rotatable abrasive wheel therein, a cam for reciprocating the work supporting means, means for rotating the work simultaneously with the reciproeatory movements of the work supporting means. a differential driving mechanism disposed between said work rotating and support reciprocating means, and means to manually adjust said differential means during operation of the machine. 1

In testimony whereof, I hereto afiix my signature.

HENRY E. DURKEE.

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