United States Patent: 3552261

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( 21636 of 21636 )

United States Patent	3,552,261
Hunkeler , et al.	January 5, 1971

BEVEL GEAR MAKING

Abstract

A bevel gear making machine is provided with a structural orientation of cradle housing, cradle, tool holder and workhead assembly wherein the tool is designed to rotate about a generally horizontal axis while the work is designed to rotate about a generally vertical axis, and wherein supporting side wall members are provided for securely holding the workhead assembly against vibration during cutting operations. This orientation of these parts may be provided at two cutting stations to constitute a unitary double machine, and such a double machine may be adapted either for two roughing or two finishing operations. Further, two of these double machines may be arranged so as to provide four adjacent cutting stations, two for roughing and two for finishing. In combination with the structure mentioned above, a control arrangement is provided for the generating train whereby a higher production rate is possible. The control arrangement and the cutting tool are provided with their own separate power sources, independent of the generating train power source, and the control arrangement for the generating train is separate from the generating train itself.

Inventors:	Hunkeler; Ernst J. (Fairport, NY), Wrubleski; Felix P. (Rochester, NY)
Assignee:	The Gleason Works (Rochester, NY)
Appl. No.:	04/764,212
Filed:	October 1, 1968

Current U.S. Class: 409/29

Current International Class: B23F 9/10 (20060101); B23F 9/00 (20060101); B23f 009/10 ()

Field of Search: 90/5,6,9.4,3,1

References Cited [Referenced By]

U.S. Patent Documents


1383707	July 1921	Farnum
2509660	May 1950	Wingren
2736238	February 1956	Moncrieff
2947223	August 1960	Carlsen et al.
3288031	November 1966	Krastel et al.
3354782	November 1967	Buchanan et al.

Primary Examiner: Weidenfeld; Gil

Claims

We claim:

1. A gear cutting machine comprising a base frame, a cradle housing mounted on said frame, a cradle journaled in said housing for rotation about a generally horizontal axis, a tool holder mounted in said cradle for rotation about a generally horizontal axis and above said frame, two parallel and spaced upstanding side wall support members attached to said frame and extending upwardly therefrom in straddling relation to said cutting tool holder, a workhead assembly disposed between and attached to said support members in a position below said tool holder, and a work holder mounted in said workhead assembly for rotation about a generally vertical axis.

2. The machine as defined in claim 1 and further including a reversing generating train operatively connected to said cradle and said work holder for imparting generating rolls thereto, said generating train including a power source with means for driving said train in reverse directions, and a control means separate from said generating train but operatively connected thereto for controlling operation thereof in both directions.

3. The machine as defined in claim 2 wherein a separate power source is provided for said tool holder.

4. The machine as defined in claim 2 wherein said control means is a servomechanism having its own separate power source.

5. The machine as defined in claim 4 wherein said servomechanism includes actuator means operatively connected to said generating train power source for controlling the effect of that latter power source on said generating train.

6. The machine as defined in claim 5 wherein said generating train power source includes a hydraulic motor and a hydraulic pump with means connecting said pump to said motor to drive the latter in reverse directions, and said servomechanism controlling the effect of said pump on said motor.

7. A gear cutting machine as defined in Claim 1 wherein said cradle, tool holder, and workhead assembly define a first cutting station and further including a second cutting station spaced from said first cutting station, said second cutting station comprising: a second cradle housing mounted on said frame, a second cradle journaled in said housing for rotation about a generally horizontal axis, a second tool holder mounted in said cradle for rotation about a generally horizontal axis and above said frame, two spaced and parallel upstanding side wall support members attached to said frame and extending upwardly therefrom in straddling relation to said second tool holder, a second workhead assembly disposed between and attached to said last-named support members in a position below said second tool holder, and a second work holder mounted in said second workhead assembly for rotation about a generally vertical axis, said first-named two support members and said second-named two support members being generally coplanar.

8. The machine as defined in claim 7 wherein said frame is of generally rectangular outline in plan view with said cutting stations being disposed at opposite ends of said frame with the two tool holders facing each other and with the workhead assemblies being disposed intermediate the tool holders.

9. The machine as defined in claim 7 and including a reversing generating train for each cutting station and operatively connected to said cradle and said work holder at that station for imparting generating rolls thereto, each of said generating trains including a power source with means for driving said train in reverse directions, and a control means separate from said generating train but operatively connected thereto for controlling operation thereof in both directions.

10. The machine as defined in claim 9 wherein a separate power source is provided for said tool holder, and wherein said control means is a servo-mechanism having its own separate power source.

11. The machine as defined in claim 10 wherein said servo-mechanism includes actuator means operatively connected to said generating train power source for controlling the effect of that latter power source on said generating train.

12. The machine as defined in claim 11 wherein said generating train power source includes a hydraulic motor and a hydraulic pump with means connecting said pump to said motor to drive the latter in reverse directions, and said servo-mechanism controlling the effect of said pump on said motor.

13. Gear cutting apparatus including a second machine as defined in claim 7 disposed adjacent to said first machine.

14. The apparatus as defined in claim 13 wherein said machines are of generally similar outline with said base frames being of generally rectangular outline in plan view and wherein said machines are arranged with said base frames in generally parallel, juxtaposed relation.

15. The apparatus as defined in claim 14 wherein the cutting stations on each of said machines are arranged in oppositely facing relation and wherein said four cutting stations are arranged to constitute corners of a generally rectangular outline.

Description

The present invention relates to gear making apparatus and particularly to machines for making bevel gears.

The present invention is part of an overall, general development of the Gleason Works which includes several inventions besides that disclosed and claimed herein. This development includes other inventions such as a novel cradle housing and cradle assembly, a novel ratio control or ratio change mechanism, novel control means for the generating train, a novel workhead assembly and mounting, novel means for conveying gears or gear blanks to the cutting stations and transferring them between cutting stations with novel means for automatic stock division in going from one station to the other, a novel control means for controlling the operation of the work loading and unloading and automatic stock division mechanisms, a novel chamfering means designed to remove burrs, etc. from the roughed gears, and other novel structures and techniques, all of which are being covered in a series of patent applications. These applications are: Ser. Nos. 764,213; 764,214; 764,221; 764,222; 764,217; 764,218; 764,219; 764,220; 764,215 and 764,216. filed of even date herewith, and the disclosures of which are all incorporated herein by reference.

While the present development relates especially to the production of bevel pinion gears for the automotive industry, for example, spiral bevel or hypoid gears, it will be apparent to those skilled in the art that features of the development may be used in machines for making other types of gears, and for industries other than the automotive industry.

It is a primary general object of the present invention to provide bevel gear making apparatus with novel structures and features that will increase the production rate of the apparatus over previous machines while at the same time satisfying the requirements for quality and precision in the final product. A further general object of the invention is to provide a novel basic design for a single gear making machine and which can be incorporated into gear cutting machines mounted or constructed as a double gear cutting apparatus wherein gear cutting operations are performed at two stations simultaneously. It is intended that the basic design, referred to, will enable the production of bevel gears to become more automated.

It is contemplated that the double gear cutting apparatus, referred to above, can be utilized either for two roughing operations, or it could be used with certain structural modifications thereto, as will be described hereinbelow, for two finishing operations. It is further contemplated that a double rougher and a double finisher, embodying the present invention, could be utilized together presenting four cutting stations, two for roughing and two for finishing, and with suitable means for conveying the work to these various stations to provide a more fully automated operation wherein gear cutting can be going on simultaneously at both stations in each double machine.

It is still further contemplated that a double rougher or double finisher embodying the present invention could be utilized with existing gear roughing or finishing machines so that, for example, a double rougher may be utilized for producing roughed gears which could then be finished on existing machinery, or a double finisher could be utilized with existing roughing machines for the purpose of finishing the gears produced by those roughing machines. It is also contemplated that a double machine, embodying the invention, could be designed so that one station does roughing and the other does finishing, as will be understood by those skilled in the art.

A further, more specific object of the invention is to provide a gear cutting machine with a novel structural orientation for the cradle housing, cradle, tool holder, workhead assembly and associated structures to enable the machine to operate at higher speed and with a greater production rate. A related object is to provide a double gear cutting machine presenting two gear cutting stations wherein each cutting station involves this novel structural orientation. The cutting stations in the double machine preferably are mounted on a base or frame and in opposed or facing relation with each other, with means being provided for conveying work to the machine, and with means for transferring the work from the conveying means to the first cutting station and then to the second cutting station, and finally to an output station, for example, back on the conveyor means.

A further related object is to provide two double gear cutting machines, each of the same basic design and with the same novel structural orientation, referred to, wherein two roughing operations are performed at the first machine, and two finishing operations are performed at the second machine. These two machines, in the illustrative embodiment shown and described herein, are both of generally rectangular outline and are arranged in side-by-side relation so as to facilitate transfer of the work from one machine to the other.

As will be understood, it is necessary in the generation of bevel gears to provide a generating train or the like to effect the desired roll between work and tool for proper cutting action. A further object of the present invention is to provide a novel combination of novel control means for the generating train with the novel structural orientation of the cradle housing cradle, tool holder, workhead assembly and associated structures whereby the time for the rolling action in each cutting cycle may be decreased and the speed of rotation of the tool increased to cut down the production time for completing the cutting cycle. In the illustrative embodiment of the invention, the control means is in the form of a servomechanism having its own source of power independent of the power source for the generating train.

It is a still further object of the invention to provide a novel process or technique of producing finished bevel gears wherein four separate gear cutting stations are provided in two double machines, one for roughing and one for finishing. Thus, a continuous single production line may be provided wherein the work is fed sequentially through four cutting stations wherein two roughing operations will be performed by one double machine, and two finishing operations will be performed on the other double machine. It is contemplated that the two roughing operations may be continued even if there is a stoppage for some reason in the finishing machine, and likewise the finishing machine can be operated even if there is a stoppage for some reason in the roughing machine.

The foregoing and other objects and advantages of the invention will appear from the following description of the preferred embodiment illustrated in the accompanying drawings, wherein:

FIG. 1 is a perspective view of a double gear cutting machine embodying the invention, and with some of the parts not shown for convenience of illustration;

FIG. 2 is a somewhat schematic, plan view, on a reduced scale, of a single gear cutting machine embodying certain features of the invention;

FIG. 3 is a somewhat schematic, plan view, on a reduced scale, of a double gear cutting machine embodying certain features of the invention;

FIG. 4 is a somewhat schematic, plan view, on a reduced scale, showing two double gear cutting machines embodying certain features of the invention;

FIG. 5 is an enlarged diagrammatic view illustrating somewhat schematically the generating train and the control means therefore embodying certain features of the invention;

FIG. 6 is an isometric and diagrammatic view of the generating train and control means therefore illustrated in FIG. 6.

Referring now to the drawings, a double gear cutting machine embodying the present invention is shown in FIG. 1. This machine is a double finishing machine, wherein each of the cutting stations does a finishing operation. However, it will be understood that a double roughing machine embodying the invention may have a similar external appearance and the same basic design with certain structural modifications adapting it for roughing, rather than finishing, as will be understood to those skilled in the art and as will be apparent from the series of applications being filed contemporaneously herewith. The double finishing machine is identified by numeral 20 and a double roughing machine 22 is shown in FIG. 4 adjacent and at the side of the finishing machine 20. Each machine includes two cutting stations as indicated by reference characters 24a , 24b , 24c , 24d and each machine comprises a frame 26a , 26b on which the cutting stations are presented.

A single machine 28 is shown in FIG. 2 and will now be described in some detail, it being understood that like reference numerals will be utilized to designate corresponding parts of the double roughing and finishing machines shown in FIG. 4. The single machine 28 can be built for use as a rougher for rough cutting of the work, or with somewhat different internal mechanisms, it can be built as a finisher capable of finishing a previously roughed gear blank. It may be built as shown for manual loading of the work, or equipped for automatic loading using an additional loader attachment (not shown).

FIG. 2 illustrates what is called the "left side" version and it includes the frame 26c, on which is mounted a cradle housing 30 containing the cradle 32 and tool holder 34. The tool holder 34 is mounted for rotation within the cradle 32 and about a generally horizontal axis which may be adjusted to a certain range or ranges of positions, as will be understood. The cradle housing and cradle structure are disclosed in more detail and claimed in the copending application Ser. No. 764,222. The tool holder, as will be understood, is designed to mount a rotary face mill cutter. The rotary tool holder, face mill cutter, and adjustable means in the cradle for adjusting the position and angle of the face mill cutter and rotary tool holder may be conventional, as disclosed, for example, in U.S. Pat. No. 2,667,818.

The single machine 28 shown in FIG. 2 also includes upstanding flanges or sidewalls 36, 38 suitably mounted on the frame 26c and extending upwardly therefrom in straddling relation to the cradle 32. As best seen in FIG. 1, these sidewalls 36 terminate at a point intermediate the height of the cradle 32. A workhead assembly 40 is mounted between these sidewall members 36, 38 and includes a rotatable work holder 42 mounted therein and designed to receive the work to be cut so that the work is rotatable about a vertical or generally vertical axis. The workhead assembly 40 and the structure for mounting the workhead assembly in the machine are disclosed and claimed in the copending application Ser. No. 764,221. As is disclosed in that application, the workhead assembly 40 is designed to be reciprocated back and forth in a horizontal direction both toward and away from the cradle and tool holder. The workhead assembly is also designed to be pivoted or rotated through a limited angle and about a horizontal axis extending between the sidewall members 36, 38, and it will be adjustable in a vertical direction in connection with initial setup of the machine, again as is described in the copending application. Additional structures disclosed in that application also include means for securely clamping or holding the workhead assembly and work in a firm and secure position during the cutting operations so as to resist vibrations or other undesirable motions that might otherwise be imparted between the work and tool.

Thus, it will be seen the machine of FIG. 2 presents a novel structural orientation for the cradle housing, cradle, tool holder and workhead assembly designed to provide increased strength, support, and stability during cutting operations, so as to minimize vibrations, etc. It will therefore be possible to rotate the tool at a higher r.p.m. so that the time for the cutting cycle for each tooth may be reduced.

The same basic structural orientation just described, and shown in FIG. 2, will be seen to be included in each cutting station in the two double machines 20, 22. Additionally, the double machines are shown as including conveyor means 44a, 44b for feeding pinion gear blanks, or pinion gears which have been roughed to the machine, and work loading and unloading, turret like structures 46a, 46b are also provided for automatically transferring the work from the conveyor means 44a, 44b to the first cutting station and then to the other cutting station of the machine associated therewith, and then finally back to the conveyor means, as is disclosed and claimed in copending application Ser. No. 764,219.

A novel control means is also provided for controlling the operation of the work loading and unloading structure 46, and is indicated schematically by reference numerals 48a, 48b, in FIGS. 3 and 4. This control means is disclosed and claimed in copending application, Ser. No. 764,220. A chamfering means indicated schematically by reference numeral 50 is shown in FIG. 4 as being associated with the conveyor means 44a adjacent the double roughing machine 22, and it will operate to remove burrs, sharp points, etc. from the gear teeth, as will be understood. Such a chamfering means is disclosed and claimed in the copending application Ser. No. 764,216.

While the conveyor means 44a, 44b are shown in FIG. 4 as extending the same direction, for each machine, it will be understood that they may extend in opposite directions, for each machine, or they may extend in other suitable directions, as toward each other, as desired. Furthermore, the chamfering means 50 may be arranged at any suitable location or any desired location, and suitable additional conveyor means (not shown) may be provided for initially feeding the pinion gear blanks on to the conveyor means 44a, and then for feeding the roughed gear blanks from the conveyor 44a to the conveyor 44b, and finally for removing the finished gears from the conveyor 44b to some suitable storage location, or the like. Thus, the entire operation may be fully automatic starting from the initial feeding of the pinion gear blanks on to the conveyor 44a and ending with the removal of the finished gears from the conveyor 44b to some suitable location.

Thus, it will be seen that the present invention includes several combinations and arrangements of individual machines for various gear cutting operations, or for producing a completely finished pinion gear from an uncut pinion gear blank. As stated above, the "left side" version shown in FIG. 2 could be used for an individual roughing or finishing operation. Or, a "right side" version (which would correspond to virtually a mirror image of the left side version) could be combined with the left side machine by mounting the two cutting stations on a single frame or base, as shown in FIGS. 1, 3 and 4 to constitute a "double" or twin machine.

As indicated, one such machine could be built for use as a double finisher, in which case the machine will be constructed and set up for finishing one side of the teeth in the left machine and the opposite side of the teeth in the right machine. Such a double finisher will incorporate the conveyor and loader and transfer means referred to above, for accepting previously roughed pinions, moving them to the work holding means at one cutting station for the first finishing operation, then transferring the work to the opposite side for the second finishing operation, and finally transferring it back to the conveyor 44b and then to a receiving station for the finished parts.

Another such double machine will be available as a two operation rougher in which one side will accept uncut blanks from the loader and perform a preliminary roughing operation. This first roughing cut may be a gashing, nongenerating cut, or it may involve a generating action. Upon completion of this operation, the transfer mechanism will then move the work to the work holding fixture on the other side of the machine where a second roughing operation will be performed, involving generation, following which the piece will be transferred back to the conveyor 44a.

It will be understood that in the operation of a double machine, it is contemplated that cutting will be going on simultaneously on two separate work pieces, one at each cutting station.

For high speed production of bevel pinion gears, for example, of the type that would be utilized on all American passenger cars and many foreign cars, a complement of two double or twin machines preferably will be employed, one for roughing and the other for finishing, each as described above, and arranged in desired relation for mass production, such as in side-by-side relation, as shown in FIG. 4, or in some other relation, as will be evident by those skilled in the art.

THE DRIVING ARRANGEMENT

It will be understood that in generation of bevel gears, such as spiral bevel or hypoid gears, there commonly are two basic elements, the cradle and the work spindle, both of these being located in a certain spaced relationship with one another and rotating in a predetermined timed relationship on their respective axes. Conventionally, the cradle carries a rotating, multibladed face mill cutter (not shown) whose axis is in adjustable but stationary position relative to the cradle, offset from and generally inclined to the axis of the cradle on which it is mounted. The cradle and cutter mounted thereupon represent the imaginary "generating gear," as is understood, and the rotating cutter blade edges represent a tooth of this imaginary "generating gear," The work spindle carries the work being cut; the cradle carrying the cutter rotates about the cradle axis in timed relation to the rotation of the work spindle with the rotating cutter in engagement with the work. Thus the imaginary "generating gear" is said to roll with the work piece.

The roll proceeds sufficiently to complete the generation of one tooth slot (or in some cutting operations, one side of one previously roughed tooth slot), whereupon there is a withdrawal so that the cradle with its cutter and the work are relatively separated one from the other in the direction of the cradle axis. The rolling motion of both cradle and work spindle is reversed during which time an increment of motion is added to the work spindle such as to advance (index) the work relative to the cradle by one pitch. At the completion of the reversal of roll, called the return roll, relative cradle axial movement between cradle and work again occurs to bring the two into cutting position, whereupon a cycle is repeated to cut the following tooth. It will be understood that, if desired for certain cutting operations, a cutting action could be provided on the return roll, after which the cutter and work will be relatively withdrawn, and the work indexed for the next tooth cutting cycle.

THE GENERATING TRAIN

The generating train of the machine, as will be understood, is the complete connection between the cradle and work spindle for controlling the relative generating rotation of these two members. The illustrative embodiment of the generating train shown in FIGS. 5 and 6 will now be traced. A worm gear 52 is fixed rotationally to the cradle 32, and this gear is engaged by a worm 54 connected to a telescoping shaft 56 on which is mounted a change gear 58. This is the point in the train where there is introduced a set of four change gears, a selection of which governs the ratio of generating roll between the cradle and work. Continuing through this latter set of change gears 60, 62, 64 through shaft 66, there is a connection to a suitable index differential gearing 68. Except during the indexing interval, which will be referred to again hereinbelow, the index differential 68 can be regarded as a simple train of gearing with gear 70 meshing with gear 72 which is rigidly connected to gear 74 meshing with a gear therebelow rigidly connected to gear 76 which inturn meshes with gear 78, as shown. Gear 78 is rigidly connected to or integral with bevel gear 80, in turn meshing with bevel gear 82 connected to shaft 84.

Shaft 84 is keyed for rotation to another bevel gear 86 engaging with a mating gear 88 fastened to a shaft 90 which is connected for rotation to a pinion 92 of a hypoid pair. The meshing hypoid gear 94 is rigidly connected to the work spindle. As will be understood, the work spindle is connected for rotation in the workhead assembly 40. This completes the trace of the generating train, that is, the gearing which links and controls the relative rotational motion of cradle and work during the generating rolls. It will be understood that this generating train will be capable of being rotated in either direction, for the forward and return rolls.

THE INDEXING MECHANISM

A suitable indexing mechanism 96 will be provided, and in this connection, reference is made to U.S. Pat. Nos. 3,229,552, and 3,283,660, the disclosure of which is incorporated herein by reference. The teachings of those patents indicate suitable indexing mechanisms that may be utilized in part in connection with the generating with the generating train, in the present invention. In an indexing step, the cradle 32 may be considered as fixed against rotation, and likewise cradle gear 52, worm 54 and related elements of the generating train, as will be evident. In the operation of the index 96, an index rack 98 will be moved in a direction perpendicular to the plane of the diagram in FIG. 5 and through a fixed distance by a suitable hydraulic piston (not shown). The rack 98 engages a pinion 100 which is made to turn exactly one revolution as a result of the controlled distance of rack travel. Pinion 100 drives a gear 102 through an axially engageable and disengageable one tooth clutch 104. During the forward or indexing stroke of the rack, clutch 104 is held in engagement by hydraulic pressure in cylinder 105, as will be understood. One turn of gear 102 produces a corresponding single turn of mating gear 106, which produces one turn of the coaxial and connected change gear 108. During the indexing motion of gears 106 and 108, a locking pawl 110 is made to disengage from a notch in a locking disc 112 connected to and corotatable with the gears 106 and 108. At the completion of the one turn, the locking pawl is made to reengage disc 112.

The change gear ratio 108, 114 is so chosen that an appropriate rotational increment is produced in the gear 114, producing in turn the identical increment in the connected differential spider 116. Spider 116 carries the differential pinions around the stationary gear 70. The action of the differential is such as to produce a turning of gear 78 relative to gear 70, equal to exactly twice the turning increment of the spider 116. The appropriate rotational increment in gear 114, controlled by the index change gear selection, must be such that the amount of turning of differential gear 78 relative to differential gear 70 will produce, by way of generating train elements 78 through 94, an increment of work spindle turning relative to the fixed cradle equal to one pitch of the work.

It will be recalled that for the purpose of explaining the function of the indexing mechanism, the cradle was considered as fixed rotationally. In actual operation, however, the indexing can be made to occur while the cradle is turning as, for example, during the noncutting portion or return roll of the cycle. The increment of index rotation produced in the work relative to the cradle is the same.

At the completion of one indexing step, hydraulic pressure in cylinder 105 will be released permitting disengagement of clutch 104 and the rack 98 and pinion 100 will be returned to their original position, before the clutch is reengaged.

THE DRIVE FOR THE GENERATING TRAIN

As shown in FIGS. 5 and 6, the drive for the generating train includes a reversible hydraulic motor 118, driving through shaft 120 and roll change gears 122, 124 and fixed gearing 126, 128, the latter gear being rigidly attached to shaft 66 in the generating train. A controllable displacement, hydraulic pump 132 is shown as being connected to the hydraulic motor for controlled and reversible driving actuation thereof in conventional manner. The pump 132, in turn, is driven by a motor 134, which in the illustrative embodiment is a constant speed electric motor. The electric motor 134, hydraulic pump 132, and hydraulic motor 118 and the various driving connections therefore may all be of conventional design.

CONTROL SYSTEM FOR THE DRIVE TRAIN

The present invention contemplates a novel control system for the drive train in combination with the novel structural orientation of the cradle housing, cradle, tool holder and workhead assembly, as referred to above. The control system, per se, is more fully disclosed and claimed in the copending application Ser. No. 764,213.

The illustrative embodiment of the control system, as best seen in FIGS. 5 and 6, includes a servomechanism 136, comprising a variable speed DC motor 138 driving through belt 140 and pulleys 142, 144, and through right angle gearing 146, 148 to a worm 150 which in turn is drivingly engaged to a worm wheel 152. The worm wheel 152 is fixed to and rotates main cam shaft 154 which is mounted for rotation suitably in a feed cam bracket (not shown) rigidly attached to the machine frame. The feed cam shaft 154 carries the feed cam 156, various hydraulic 158 and electrical 160 trip cams (for various purposes, such as producing appropriate timing for such functions as hydraulic pressure and release to the indexing mechanism, ratio control and various set overs as will be understood). A rise end cam, called a roll cam 162, is also driven by the cam shaft 154. The variable speed motor 138 will be adjusted to regulate the cycle time of the entire machine. In the present embodiment of the invention, one turn of the main cam shaft 154 will produce one tooth cutting cycle.

A roll cam follower roller 164 is mounted on a nut 166 of a nut and screw 168 assembly, constituting a differential connection between the cam shaft 154 and the generating train, as will be apparent. The nut will be constrained against rotation but is free to translate or move axially. The screw 168 is free to translate axially and to rotate within the nonrotating nut 166, and the lower end of the screw, as shown in the drawing, bears on or against a pivoted lever 170, the free end 172 of which is arranged to actuate a hydraulic control valve system 173, of conventional design, and which includes a wobble plate valve (not shown). The wobble plate valve is designed to govern the direction and flow rate of the discharge of the pump to the hydraulic motor, and this establishes the direction and rate of motor rotation, as is understood.

A compression spring 174 is shown continuously urging the actuator 170 and screw 168 upwardly, as shown in FIG. 5, so as to urge the follower 164 into engagement with the roll cam 162.

When the cam 162 rotates from the position shown in FIG. 5, the follower 164, nut 166, screw 168 and actuator 170 will tend to move upward, as viewed in FIG. 5, as urged by the spring 174.

This movement will result in a valve movement permitting the pump to discharge fluid (for example, oil) at a certain rate and such as to rotate the motor 118 in the direction shown by the arrow. Fixed for rotation with the motor output shaft 120 is a gear 176 which is engaged to gear 178 fixed for rotation with screw 168. Rotation of the motor resulting from movement of the pump control valve regulating flow of the driving fluid to the motor will thus effect rotation of the screw 168 through the gears 176, 178, such that the screw 178 will thread itself downward within the nut 166 and tend to restore the lever 170 and control valve 173 to their original or neutral position. The lever and control valve will be restored to that neutral position unless further falling of the cam path, permitting further upward movement of the nut 166, results in a command for continuous discharge from the pump 132 to the motor 118. The pump 132 and motor 118 will both be of the positive displacement type, in the illustrative embodiment, and thus it will be seen that a given rise or fall of the cam will produce a corresponding fixed number of turns of the motor 118, and the established rise of the cam 162 will produce a fixed number of turns each way of the shaft 120 per tooth cutting cycle.

Selection of the appropriate roll change gears 122 and 124 produces from the fixed number of turns of the shaft 120 a desired angle of turning in the work spindle, as required to fully generate one tooth contour. Selection of the ratio of roll change gears 58, 60, 62 and 64 in the generating train will produce the proper proportionate angle of cradle turning, as will be apparent. Thus, by suitable choice of these roll change gears and ratio of roll change gears the desired amount of roll for the work spindle and cradle can be predetermined, for example, depending upon the requirements of a particular cutting operation and cycle. However, the present development also contemplates a separate and novel means for effecting a change in this ratio of roll between the cradle and work spindle during operation so as to produce a different ratio of roll in one direction of roll than in the other direction of roll, as may be desired for certain cutting operations, for example, in the generation of spiral or hypoid pinion gears. This means for changing the ratio of roll, separate from the ratio of roll change gears mentioned above, is more fully disclosed and claimed in the copending application Ser. No. 764,214.

The feed cam 156, operating from the main cam shaft 154 for cycle control, preferably is arranged to actuate the cradle 32 axially into and out of generating position with the work, and in general this will take place once per cutting cycle, as will be understood. The structure for effecting this axial movement of the cradle is disclosed and claimed in the copending application Ser. No. 764,222.

THE CUTTER DRIVE

The cutting tool, tool holder 34, and the cutter drive train are shown in FIG. 5 as driven by a separate power source, for example, an electric motor 177, through speed change pulleys 179, 181 and belt 183, and a train of gearing 185 within the cradle. This gearing may be of conventional design as disclosed, for example, in U.S. Pat. Nos. 2,667,818 and 3,288,031.

HELICAL MOTION AND RATIO CONTROL MECHANISM

In the lower part of the drive diagram shown in FIG. 5, there are illustrated both a helical motion and a ratio control mechanism of the present development. The helical motion mechanism 186 is utilized for some cutting methods on some finishing machines, and it is not contemplated that it will be used in any roughing operation. The helical motion mechanism is disclosed more fully in copending application Ser. No. 764,222.

The ratio control or ratio change mechanism 188 is intended to be used only during a roughing operation, and not during a finishing operation. Thus, while both the helical motion mechanism and ratio control mechanism are shown in the diagram of FIG. 5 for illustrative purposes and for convenience of illustration, it will be understood that both mechanisms will not be utilized in the same machine at the same time. The ratio change mechanism is disclosed more fully in copending application Ser. No. 764,214.

The helical motion mechanism 186 is designed to effect, from the rotational motion of the cradle 32, the cradle axial motion and in timed relation with the rotation. As shown, this is accomplished by means of a gear train, starting a large gear 190, coaxially fixed to the cradle for rotation therewith, and driving pinion 192, then through a train 194 driving a cam 196. The cam 196 operates through a follower mechanism and other structures (not shown) for actuating the cradle feed yoke 197 to effect the axial movement, as is disclosed more fully in copending application Ser. No. 764,222. It will be understood that this axial feed of the cradle is in connection with a cutting movement, whereas the withdrawal of the cradle, for example, in connection with indexing, will be accomplished through the feed cam 156 described above in connection with the servocontrol mechanism 136.

The ratio control mechanism 188 of a rougher functions in combination with a tooth rough cutting operation in which cutting takes place in the tooth slot during both the up and down roll, with the brief pause for cradle withdrawal and work index at the end of the return roll. For up and down roll roughing, the ratio control mechanism 188 is engaged during one roll direction only. While engaged it adds or subtracts a steady increment of turning to the cradle by moving the cradle worm 54 axially, thereby producing a different ratio of cradle to work roll. The ratio control mechanism 188, as shown in FIG. 5, includes a train of gears beginning with gear 198 driven from the gear 176 on shaft 120, and further includes hypoid gears 200 and ratio control change gears 202. These latter gears are connected through gearing 204 to a cam 206 which moves follower roller 208 and follower 210. The latter movement drives the worm 54 axially, as is disclosed in copending application Ser. No. 764,214.

DRIVE CONNECTION WITH THE RIGHT SIDE OF A DOUBLE MACHINE

The drive arrangements just described and as shown in FIGS. 5 and 6 are designed for the cutting station at the left side of the machine, and it will be understood that the drive arrangement for the cutting station at the right side in a double machine preferably includes a similar or identical driving arrangement (not shown).

It is contemplated that the timing cycle for the cutting station at the right side of this machine will be controlled by a mechanical connection illustrated as being in the form of a through shaft 212 from pulley 144 and gear 146 to the gears 146', 148' at the right side of the machine, as shown in FIG. 6, such that the cycle control cam shafts 154, 154' for both sides of the double machine are driven by the variable speed motor 138 at the left side of the machine.

THE LOADER-TRANSFER MECHANISM

As disclosed in the copending application SER. No. 764,219 covering the loader-transfer mechanism 46, it has no mechanical drive connection with the cutting mechanism of the machine, but is provided with its own power source. However, it is contemplated in one embodiment thereof that an electrical impulse for starting the loader function be derived from the machine operation. Additionally, there may be provided various control interlocks with the machine to protect against misfunctions or the like, as will be understood from the disclosure of that application.

INCREASE IN PRODUCTION

One of the reasons for the increase in production provided by the present invention is that the cutter may now be operated at a much higher speed, as indicated above. This is possible because, among other things, the cutter drive and gearing have been separated entirely from the generating train, and a novel structural orientation of tool and work holders and supporting structures has been provided to withstand the higher cutting speeds. Furthermore the control means for the generating train is separate from it and is operated by its own independent power source, while the generating train has its own separate power source. This also enables the generating train to operate at higher speeds so as to accommodate the faster cutting cycle. In typical previous machines, the means for controlling the operation of the generating train actually drove the generating train itself, as disclosed, for example, in U.S. Pat. No. 2,667,818. While such structures were and still are satisfactory for commercial production, the present development is designed to constitute an improvement thereover by providing for an even higher production rate.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of this invention and is subject to extensive change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

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Current U.S. Class:	409/29
Current International Class:	B23F 9/10 (20060101); B23F 9/00 (20060101); B23f 009/10 ()
Field of Search:	90/5,6,9.4,3,1