US2121479A - Machine for finishing gears - Google Patents

Description

R. s. DRUMMOND I 2,121,479

MACHINE FOR FINISHING GEARS June 21, 1938.

Original Filed April 11, 1932 4 sheets-Sheet l INVEN TOR ROBERT S. DRUMMOND W ATTORNEYS June'Zl, 1938. R DRUMMOND 2,121,479

MACHINE FOR FINISHING GEARS Original Filed April 11, 1932 4 Sheets-Sheet 2 INVENTOR ROBERT s DRUMMOND MW Am I ATTORNEYS June zl, 193s. R D MM ND 2,121,479

MACHINE FOR FINISHING GEARS Original Filed April 11, 1932 4 Sheets-Sheet 3 INVENTOR ROBERT SDRUMMOND Y Hum-cm 4 flay TTTT RNEY S R. S. DRUMMOND MACHINE FOR FINISHING GEARS Originl Filed April 11 1932 4 Sheets-Sheet 4 INVENTOH ROBERT S DRUMMOND ATTORN EYS BY wmww June 21; 1938.

Patented June 21, 1938 PATENT OFFICE 2,121,479 momma ro'a FINISHING ems Robert S. Drummond, Detroit, 'Mich.

Original application April 11, 1932, Serial No.

604,575, now Patent No. 1,989,651, dated Janu- Divided and this application January 26, 1935, Serial No. 3,663. In Great Britain August 17, 1931 3 Claims.

The invention relates to machines for finishing gears by lapping, burnishing, cutting or similar methods. This application is a division of my application, Serial No. 604,575 filed April 11, 1932, now Patent No. 1,989,651 and is a continuation in part of my applications, Serial Nos. 547,704, filed June 29, 1931 now Patent No. 1,989,650; 626,769, filed July 30, 1932 now Patent No. 1,989,652 and 626,768, filed July 30, 1932 in which certain novel methods of finishing gears have been claimed.

The principal object of the present invention is to obtain a machine adapted for the lapping, burnishing or cutting of gears by means of a rotary finishing tool, the axis of which lies in no common plane with the axis of the work gear and is crossed at an angle of less than 30 therewith. Other objects reside in the construction by means of which the machine is adapted to produce great accuracy at a high rate of production and with simplicity of operation.

In its broader aspects my invention contemplates various types of machines in which special features have been incorporated making them adaptable for the finishing of gears in accordance with this and my co-pending applications above referred to. Thus my invention may be practiced by. modifying certain prior art machines in such a way as to obtain a diiferent 1organization adapted for producing a new funcion.

In the drawings:

Figure 1 is a side elevation of one form of gear finishing machine;

Figure 2 is a plan view thereof;

Figure 3 is a sectional elevation showing the relation between the finishing tool and the gear to be finished;

Figure 4 is a section through a portion of the gear and finishing tool engaging each other with cramp action;

Figure 5 is a view similar to Figure 4 showing the modified en agement when a'power tail stock is used;

Figure 6 is a perspective view of a modified machine;

Figure 7 is a vertical section through the construction shown in Figure 6;

,Flgure 8 is a sectional view illustrating the portion of the drive mechanism taken substantially on the line 8-8 of Figure 7;

Figure 91s a horizontal vertical view taken substantiallyon the line 9-9 of Figure 7;

Figure 10 is a sectional view through the arbor for the finishing tool; 1

Figure 11 is a diagrammatic sectional view through the oil pump.

The invention in its broadest aspects may be embodied in a machine which may be considered as a reorganized milling machine. Thus as illus- 6 trated in Figures 1, 2 and 3, 30 is a universal milling machine of ordinary construction pro-1 vided with a bed 3| which may be raised or lowered by suitable mechanism such as the screw 32 controlled by the handle 33. On the bed 3| 10 there is a carriage 34 movable toward and away from the column 35 by a handle 36. 31 is a table universally mounted at 38 on the carriage 34 and adjustable to the desired angularity in the conventional manner. The table 31 may be longitudinally adjusted by means of the screw 39 and handle 40. Above the table 31 is an arbor 4| which projects horizontally from the column 35. The arbor is journaled in a bearing 42 in the column and has its outer end journaled at 43 in an adjustable slide 44 which is supported and projects from the upper portion of the column 35.

Mounted on the table 31 is a fixture 45 comprising a plate 46 adapted to be secured to the table by fastening screws 41 and a vertical portion 48 for rotatably supporting the arbor 49. The arbor 49 is prevented from axial movement by thrust bearings 50 and 5| at the opposite ends of the bearing 52. The arbor 49- projects from the bearing in the fixture and is adapted to have removably mounted thereon the gear D. The arbor M .is adapted to have mounted thereon .the gear'I. The gears D and I are selected so as to have a mating engagement when the arbors 49 and 41 are arranged at the desired angle for the finishing operation. One of the gears is the gear which it is desired to finish and the other is in the form of a finishing tool. As

shown, the gear D is the gear to be finished and is provided with spur teeth, while the gear I is the finishing tool and is a helical gear. The axes of the gear and finishing tool lie in no common plane and are crossed at the desired angle in accordance with the method outlined in my copending applications above referred to. The angle between the axes may be adjusted by the angular setting of the table 37 on its universal mounting. The rotation of'the finishing tool' and gear is provided by rotating the arbor 4| by suitable mechanism indicated generally by the numeral 53.

In order to adjust the angularity-ol' the axes of the gear and finishing tool, it may also be desirable to adjust the fixture 45 in order to vary 56 the angle of the arbor 49 with respect to the longitudinal axis of the table 31. In some instances it may be desirable to have the arbor 4i carry the gear to be finished and the arbor 49 support the finishing tool. It will be noted that when it is desired to feed the gear relative to the finishing tool in the direction of the axis of the arbor 4|, this may be accomplished by turning the handle 36. When axial feed is required parallel to the axis of. the arbor 49 and the longitudinal axis of the table 91, it may be accomplished through the handle 40. For obtaining a predetermined contact pressure between the teeth of the gear and the finishing tool the handle 33 is used.

In the operation of the machine as thus far described, the method described in my co-pending applications should be practiced in order to secure the best results. In accordance with said methods, the gear finishing tool and the gear to be finished have conjugate mating teeth and the angle betweenthe axes is preferably maintained between a lower limit usually more than 3 and an upper limit less than 25 to 30. If the gear to be finished is a straight spur gear, the finishing tool will be a helical gear having a helical angle within the above limits. On the other hand, if the gear to be finished is helical, the finishing tool may be in the form either of a straight spur gear or of a helical gear, but in each case the difference in helical angle should be such that when in proper mesh the angular difference between the axes is within the limits previously mentioned.

In the machine previously described and illustrated in Figures 1 to 3, an embodiment oi. the invention has been disclosed, but in order to obtain the best results from my invention it is preferable to provide a machine of a modified type such as is hereinafter described and illustrated in Figures 6 to 11 inclusive. In the modified construction the machine is adapted to automatically perform the principal movements required. The machine is provided with a hollow base 60 which at a convenient height is provided with a table 9|. At the rear of the table are segmental ways 62 on which is mounted a vertical column 69. At the front of the table 6| provision is made for carrying the arbor 64 on which the finishing tool 65 is mounted. This consists of a head stock 66 and tail stock 61, the latter being adjustable in the ways 69 on the table 6I-. These are so located that the horizontal axis of the arbor 64 intersects the vertical axis about which the column 63 is angularly adjustable on the ways 62. For adjusting the finishing tool axially there is provided the square shank 69 which carries at its opposite end the pinion 10 (see Figure 10). rack H on the sleeve 12 which in turn has a collar 13 abutting the finishing tool 66. Thusupon rotation of the square shank 69 with a suitable handle, the finishing tool 95 may be axially adjusted in the bearings on'the head stock 66 and tail stock' 61. q

The column 69 is provided with vertical ways 14 for mounting the crosshead 16. The crosshead is in turn provided with horizontal ways 16 on which is horizontally adjustable a carriage 11. This carriage has depending therefrom arms 19 and 19 in which are mounted bearings for the arbor 90 for the gear 9| to be finished. For vertically adjusting the arbor 60, the following mechanism is used. The column 69 is provided at the top thereof with a frame I! in which a handwheel 99 is journal'ed. The handwheel carries a The pinion 10 meshes with the gear.

worm 84 engaging a worm wheel 85 which in turn is mounted on the adjustment screw 96 This screw threadedly engages a nut 81 on the crosshead 15 while it is provided with suitable thrust collars 89 to prevent axial movement thereof. The screw also carries at its upper end the index wheel 89 for indicating the vertical adjustment of the crosshead.

- The arbor 64 is driven by suitable means such as the pulley 90 which is connected by a belt 9! to a pulley 92 on a shaft 99 arranged in the bottom of the hollow base 60. The shaft 93 has a gear 94 engaging'worm 95 on a shaft 96 driven by an electric motor 91. The speed of rotation of the arbor 64 for the finishing tool may be suitably regulated by providing the proper ratio of the gears in the driving mechanism. Provision is also made for automatically reciprocating the carriage 11, this comprising a rack 99 on the carriage 11 engaging a gear wheel 99 splined upon a vertical shaft I00 which is oscillated by a rock arm IOI connected to a link I02 engaging an ad- J'ustable throw crank I03 on a shaft I04. The shaft I04 is driven through the medium of a reduction worm gearing I05 from the shaft 93. Thus the rotation of the shaft 99 rotates the gear finishing tool 65 and at the same time reciprocates the gear to be finished in the direction of the axis of the latter. The amplitude of movement is determined by the throw of the adjustable crank I03 which may be set according to the width of the gear which is being finished. The rate of axial feed of the gear may be determined by the proper gear ratio.

In carrying out gear finishing methods as outlined in my co-pending applications a'bove referred to, it is sometimes desired to produce a cramp action between the finishing tool and the gear to be finished. This is accomplished in the present machine by operating the \wheel 83 to obtain the desired pressure between the axis of the gear and the axis of the finishing tool. The engagement of a gear and finishing tool under conditions of cramp action is illustrated in Figure 4.

In a modified method of gear finishing set forth in my co-pending applications, it is sometimes desirable to develop the desired pressure between the teeth of the finishing tool and the gear to be finished by retarding the rotation of the gear. A suitable mechanism for this purpose will therefore be described.

Mounted on the carriage 11 and preferably upon the adjustable tail stock I06 of the carriage is a gear pump I01 which is driven from the shaft 80 through the medium of intermeshing gear wheels I08 and I09. The oil or other fluid propelled by the pump is supplied by a reservoir H0 and is discharged against the resistance of a spring closed valve. The pressure of the spring may be varied by an adjusting screw II! so as to produce any desired resistance to the rotation of the pump and consequently to the rotation of the The construction is such as to resist rotation of the gear in-either direction. Thus in the operation of the machine, the driving motor 91 may be first operated in one direction for a sufiicient length of time to properly finish the faces of the teeth on one side thereof and then by reversing the motor the opposite faces of the teeth are correspondingly finished. In each instance the lag or resistance of the pump I01 will give a substantially constant pressure of contact between the teeth of the gear-and those of the finislang tool so as to produce a definite finishing ac on.

Both of-the machines previously described are useful in the finishing of gears which have been previously roughed out to approximate dimensions by other suitable means. In illustrating the machine shown in Figures 1 to 3, I have shown the gear D in mesh with a lapping tool I preferably of cast iron and the finishing action is obtained by reason of the abrasive compound which is spread on the teeth by suitable means such as by permitting the gear D to dip into a tank N containing the abrasive or lapping compound. In' operating the machine for lapping purposes the machine is set in motion thus rotating the finishing tool I which in turn causes the gear D to be rotated due to the intermeshing action of the teeth. The lapping action is continued with suitable vertical adjustments of the table from time to time by means of the handle 33 until the desired amount of stock has been removed. During the running of the gear and finishing tool in mesh the gear D is reciprocated axially in order that the finishing action will take place over the entire face width of the gear. In the illustrated arrangement the reciprocation may be obtained by means of the handle 40 or if desired by automatic mechanism, the amount of reciprocation being somewhat in excess of the face width of the gear. If desired a reciprocating movement may also be imparted in the direction of the axis of the lap in order that the wearing action upon the lap may be distributed over the face thereof. This may be obtained by means of the handle 36 which will move the table 31 in the direction of the axis of the arbor ll. This movement is unnecessary for the uniform finishing of the gear and is used only for distributing the wear on the lap. It should be somewhat less than the face width of the lap so that at no time will the lap run out of contact with the gear. Where there is no appreciable wearing action on the finishing tool the feed movement in the direction of the axis of the finishing tool is not necessary. In cases where the positions of the gear and lap are reversed with the gear to be finished mounted on the arbor .M, the reciprocating feed motion in the direction of'the axis of the gear to be finished may be obtained by the handle 36 which causes the finishing tool on the arbor 49 to be moved in a direction parallel to the axis of the arbor M.

The machine illustrated in Figures 6 to 11, is constructed to be of particular utility in carrying out the gear finishing methods described in my copending applications, whether for the purpose of lapping, burnishing or cutting. As illustrated in Figure 6, hOWejL-GI, the gear iii to be finished is shown in operative relation to the lapping tool 65, the width of which is considerably greater than the width of the gear to be finished. :Thus after the lap becomes worn in one portion thereof it may be axially adjusted by means of the square shank 69 to bring a different portion thereof into active use. When desired the machine shown in Figure 6 may be used for. lapping by means of cramp action in the same manner as previously described in connection with the machine shown in Figures 1 to 3. In such case the driving of the lapping tool 65 by the electric motor 9'! causes I1 and the gear Bl. This movement is of sum- This movement is obtained through cient amplitude to spread the finishing action over the entire face-width of the gear. The cramp action is obtained by periodically causing a down feed by means of the hand wheel 83 until the desired amount of stock has been removed.

The machine shown in Figure 6 is particularly designed to be used for finishing the gear by a method in which the pressure between the teeth of the gear andthe finishing tool is obtained by loading or resisting rotation of the driven member. In this case the finishing tool is provided with a tooth thickness that is less than the interdental spaces in the gear prior to lapping which enables the original setting of the-machine with the gear and finishing tool in full mesh, that is, with their axes spaced: apart the exact distance for normal operation. When the machine is operated by the resistance method the hydraulic brake mechanism previously described is utilized to retard the rotation of the driven shaft 80 on which the gear 8| is mounted. The driving motor 91 is first operated in one direction to finish the tooth faces on one side thereof and then by reversing the motor the opposite faces of the teeth are correspondingly finished. .During the rotation the reciprocation of the gear BI in the direction of its axis is continuously maintained in' order to distribute the finishing action over the entire face width. The resistance to rotation of the driven shaft 80 by the hydraulic gear pump I06. will give a substantially constant pressure of contact between the teeth of the gear and the finishing tool so as to produce the desired finishing action.

Where it is desired to finish a gear by a cutting action rather than by a lapping action a suitable modified form of finishing tool is employed. This is described in detail in my application, Serial No. 3,662, filed on even date herewith and will not be further described in this application. Where the term rotary finishing tool is used in the specification and claims, it is meant to include within its meaning constructions useful for lapping, burnishing or cutting.

What I claim as my invention is:

l. A machine for finishing gears comprising a frame, a horizontal arbor mounted thereon, a column extending upward from said frame and adjustable in an arcuate path concentric with the vertical axis passing through said arbor, a crosshead vertically adjustable on said column, acarriage transversely slidable on said crosshead, an arbor mounted on said carriage adjustable into variable angular. relation with the arbor on said frame by the adjustment of said column, one of said arbors being adapted to mount a gear to be lapped, a lapping tool having conjugate teeth mounted on the other arbor in intermeshing relation with said gear, means for rotating the arbor on the frame, means for reciprocating said carriage and a hydraulic brake for resisting rotation of the arbor on said carriage to produce a predetermined contact pressure between the teeth of the lap and the gear.

2. A machine for finishing gears comprising a frame, a horizontal arbor mounted thereon, a column extending upward from said frame and adjustable in an arcuate path concentric with a vertical axis passing through said arbor, a crosshead vertically adjustable on said column, a caring conjugate teeth mounted upon said horizontal arbor,- means for rotating said horizontal arbor and a hydraulic brake mounted on said tail stock driven from the arbor engaging the same and resisting the rotation thereof to produce a predetermined contact pressure between the teeth of the lap and the gear.

3. A machine for finishing gears comprising a frame, a horizontal arbor mounted thereon, a

10 column extending upward from said frame and adjustable in an arcuate path concentric with a vertical axis passing through said arbor, a cross head vertically adjustable on said column, a carriage transversely slidable on said cross head, an arbor carried by said carriage, said arbors adapted to support an intermeshed gear and a gear like finishing tool, means for rotating one of said arbors, and means for providing pressure contact between meshed teeth ofsaid gear and tool.

ROBERT s. DRUMMOND.

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