Europaisches Patentamt

J) European Patent Office CD Publication number: 0 094 392

Office europeen des brevets B1

EUROPEAN PATENT SPECIFICATION

Date of publication of patent specification: 08.02.89 Intel.4: B 23 F 5/22, B 23 F 5/24

Application number: 82902557.6

Date of filing: 06.07.82 International application number: PCT/US82/00910

International publication number: WO 83/01752 26.05.83 Gazette 83/13

IMPROVED DRIVE TRAIN FOR MACHINE.

Priority: 23.11.81 US 323775 Proprietor: THE GLEASON WORKS 1000 University Avenue Rochester New York 14692 (US) (§) Date of publication of application: 23.11.83 Bulletin 83/47 Inventor: HUNKELER, Ernst J. 22 Bittersweet Road Publication of the grant of the patent: Fairport, NY 14450 (US) 08.02.89 Bulletin 89/06 Representative: Harrison, David Christopher Designated Contracting States: etal CHDEFRGBLINLSE MEWBURN ELLIS & CO 2/3 Cursitor Street London EC4A1BQ(GB)

References cited: DE-A-1 527 126 DE-B-1 056453 GB-A-484928 US-A-1 570372 £0 US-A-2 773 429 US-A-2856 834 US-A-3 078 767 CM US-A-3971293 O) CO o mention of the of the o Note: Within nine months from the publication of the grant European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been a. paid. (Art. 99(1) European patent convention). m Courier Press, Leamington Spa, England. EP 0 094 392 B1 Description that worm drives tend to wear excessively and create heat during normal operation. The In the context of this specification, references to development of excessive heat in any given area "hobbing" or a gear hobbing process are of a machine drive train creates a special problem intended to include those machines and pro- 5 of maintaining accuracy in the drive train and can cesses which utilize a rotating tool for engaging lead to hot areas in the machine itself that tend to and forming teeth in a rotating workpiece while affect precision alignment of basic machine com- the tool and the workpiece are rotated together in ponents which determine the precision relation- a timed relationship. The timed relationship is ship between the tool and the workpiece. critical to the formation of teeth of the right 10 In order to provide for a greater range of speeds geometry and spacing about the perimeter of the in a single machine than is possible with worm workpiece, and the timed relationship is achieved drives, while, at the same time, obtaining greater with a drive train which interconnects a spindle efficiency and stiffness in the drive train of the for driving the tool with a spindle for driving the machine than is obtainable with worm gear workpiece. 15 drives, the present invention utilizes a hypoid Hobbing machines are well known in the art gear set (known per se from US— A— 2 773 429 and are utilized for manufacturing spur and heli- which describes the closest prior art in combina- cal . Typically, such machines include a tool tion with spur gears (known per se from GB — A — head portion where a cylindrical hobbing tool can 484928) in the final drive system for a work be mounted and rotated on its axis while the tool 20 spindle of a hobbing machine. The hypoid gear is brought into engagement with one or more set (or a set) functions to change the workpieces mounted on a workpiece spindle. The direction of the power train (from a horizontal to a workpiece spindle may be designed to carry only vertical axis) and to partially reduce speed at the a single workpiece or a stack of workpieces, and work spindle, and the spur gears function to the machine is provided with mechanisms for 25 further reduce speed at the work spindle. By feeding the tool into engagement with the work- separating speed reduction into two steps, it is pieces and for then traversing the tool from one possible to obtain a wider range of work spindle end of the stack of workpieces to the other end speeds with a given hypoid gear set, and the thereof while the tool and the workpieces are hypoid or bevel gear set does not have to be as rotated in a timed relationship. 30 accurate (or as costly) as is required for a worm Although bevel gears were used at one time in drive of a conventional machine. Hypoid gears the part of the drive train that drives the work- offer similar driving characteristics to what is piece about its axis (as shown, for example, in obtained with worm gears because of the number U.S. Patents 1,543,031, 2,048,503 and 2,704,492), of teeth which are in contact between the hypoid the hobbing machine technology has developed 35 and the hypoid gear which is being driven in more recent years to one which utilizes one or by the pinion. Also, hypoid drives are relatively more worm drives in the final drive system for quiet and do not create excessive heat. A hypoid providing a rotating moment to the workpiece drive also offers the possibility of an extended drive spindle. Examples of worm and wheel speed range for any given machine, and it is drives are shown in U.S. Patents 3,232,169 and 40 contemplated that a machine utilizing the drive of 3,318,193. The use of worm drives developed out this invention will be able to operate with work of a need for great precision in the final portion of spindle speeds on the order of 1 20 revolutions per a drive train where there is a requirement to minute or more. change direction of the power train and to greatly There is a particular advantage in using a reduce its speed for driving the work spindle of 45 hypoid gear set (or even bevel gears) for reverse the machine. Worm and wheel drives provide hand hobbing operations and for a such a dual function of changing direction and control system which utilizes a supplemental reducing speed in the drive train. However, worm drive train in combination with the main drive drives are costly to manufacture to the standards train of the machine. It is possible with such a of precision that are required for present day so system to preload a substantial portion of the production machines, and the use of a worm main drive train, so as to remove backlash there- drive limits the speed range available for any form, in accordance with the type of cutting being given machine. As a result of this, many com- performed by the machine. For example, a posi- panies in the business of manufacturing hobbing tive preload can be used when cutting helical machines offer two separate lines of machines: a 55 gears with a hobbing tool which is of opposite standard machine for use at standard speeds and hand from the helix of the workpiece. Negative a special machine with multi-lead worm and preload can be used when the hand of the tool worm wheels for use at higher speeds. Alterna- and the workpiece are the same. In both cases, it tively, it possible to build two separate worm is possible to effectively stiffen a substantial part drive mechanisms into a single machine, as 60 of the machine drive train through the use of a shown for example in U.S. patent 4,286,479. In supplemental drive. In accordance with the inven- either case, a customer must invest considerable tion, therefore, a motor is used to apply moment capital in order to obtain a capacity for operating to the final drive system through the supplemen- over a wide range of speeds. In addition to the tal drive. disadvantages just mentioned, it is also known 65 In US — A — 3971293 a supplemental motor was EP 0 094 392 B1 work provided, but was not coupled in such a way as to spindle 14 which supports one or more into remove backlash from the final drive connection pieces 16 for being brought working engage- to the work spindle. ment with the hobbing tool 10. Interconnecting 16 is In a preferred embodiment of the invention, the the hobbing tool 10 and the workpiece a includes drive train of a hobbing machine is provided with 5 relatively conventional drive train which drive motor be, a final drive system for its work spindle charac- a main drive motor 18. This may terized by the use of a hypoid pinion mounted to for example, a 11.0 kW (fifteen horsepower) the main be rotated by a main drive train of the machine single speed AC motor. Power from and with the hypoid pinion being in meshing drive motor 18 is transferred through a pulley 20 with a hypoid ring gear. The hypoid 10 and 22 to another pulley 24 which is con- engagement the ring is operatively connected to the work nected to a drive shaft 26. By changing pulleys gear tool 12 spindle through an indexing set which 20 and 24, rotational speed of the spindle is connected directly to the work spindle. In can be changed, and speeds in the range of 100 to in addition, a motor-driven supplemental driving 600 revolutions per minute can be provided a with this invention. system is provided for overcoming load interrup- 15 typical machine in accordance drive shaft 26 tions on the work spindle so as to remove back- Power is transferred from the lash in the that are driving the work spindle. through bevel gears 28 and 30 to another drive gears shaft 34 This combination of a final drive system utilizing a shaft 32. The drive shaft 32 is splined to a combined shafts 32 and 34 can hypoid gear set with a supplemental driving so that the another to thereby system also permits an easy adaption of the 20 telescope relative to one machine to reverse hand hobbing operations. In adjust to the axial feed of the tool relative to a addition, the hypoid drive also allows the final workpiece. Power is taken off from the drive to be made much larger than the shafts 32 and 34 through bevel gears 36 and 38 for indexing gear of rated diameter capacity of the machine which is a delivery through a drive shaft 40, another set desirable feature. 25 gears 42 and 44, a shaft 46, and a pair of spur These and other features and advantages of the gears 48 and 50 which directly drive the tool invention will become apparent in the more spindle 12 in a manner well known in this art. detailed discussion which follows. In that discus- Power is also taken off from the drive shaft sion reference will be made to the accompanying through a pair of gears 52 and 54 which transmit drawings as briefly described below. 30 power to a drive shaft 56 that transmits power to a to Figure 1 is a schematic layout of a drive train for series of gears 60 through 72 for a 66 and 68 a hobbing machine utilizing a hypoid pinion and final drive assembly. The gears 62, 64, and function to determine the gear in a final drive system for the work spindle of are changeable the machine; number of teeth to be cut in a workpiece. drive shaft Figure 2 is a layout similar to Figure 1 showing 35 The final drive assembly includes a and a modification of the drive train to include a 76, a hypoid pinion 78, a hypoid ring gear 80, differential for adjusting the rate of feed of the a spur pinion 82 which drives a spur gear 84 that machine during a hobbing operation; is directly connected to the workpiece spindle 14. the of Figure 3 is a top plan view, partly in cross- It is in this final drive assembly that use a for section of a final drive system for a hobbing 40 hypoid pinion 78 and hypoid gear 80 provide machine assembled in accordance with the the improved characteristics of a hobbing the inven- present invention; machine in accordance with present machines Figure 4 is' a detailed elevational view, partly in tion. Typically, conventional hobbing section, of a hypoid pinion and gear assembly for have required the use of a precision worm gear for simul- imparting rotational moments to a work spindle 45 system in the final drive assemblies of a hobbing machine, as seen on line 4—4 of taneously changing direction and reducing speed Figure 3; of the power train. However, by using a hypoid the Figure 5 is a detailed elevational view, partly in gear set (made up of the pinion 78 and gear section, of a supplemental driving system used in 80), it is possible to change direction of the power full conjunction with the final drive system of Figures so train without having to reduce speed for the 3 and, as seen on line 5 — 5 of Figure 3; and amount of reduction needed at the work spindle. train is Figure 6 is a schematic view of the supplemen- Final reduction of speed of the power tal driving system of Figure 5. provided for separately with the spur gear set As Figures 1 and 2 show schematic layouts of drive (made up of the pinion 82 and the gear 84). a trains for two different types of machines which 55 result, the system can operate over a wider range and less heat can be assembled in accordance with the present of driving speeds with less wear invention. The Figure 1 embodiment illustrates a than would be experienced with conventional drive train which does not include a differential drive systems. Also, the spur gear 84, which assembly within the drive train. The Figure 2 functions as an indexing gear for the work spin- embodiment illustrates the use of a differential in 60 die, can be made with a much larger diameter the machine drive train. than is conventional for machines utilizing worm Referring to Figure 1,the layout shows a tool 10 drives, and this increases the accuracy of the final which is in the form of a conventional hobbing drive system. tool which can be mounted on a tool spindle 12. The final drive system includes an anti-backlash At the other end of the drive train is a work 65 system which acts upon the spur gear 84 to EP 0 094 392 B1 overcome any changes in load encountered by the final drive assembly for the drive train of this the interrupted cutting action of the hobbing tool invention. It can be seen that the drive shaft 76 with the workpiece. This can be accomplished enters the final drive assembly area and is con- with a known braking system or with supplemen- nected to the hypoid pinion 78 for driving a tal driving system that applies a driving com- 5 hypoid gear 80. The hypoid gear 80, in turn, ponent to the spur gear 84 with a small high slip transmits its power to a spur pinion 82 which AC motor 86 operating through a bevel pinion 88 drives a larger spur gear 84 connected to com- and ring gear 90 (which may be either spiral or ponents which drive the work spindle 14. Details straight bevel gears) and through a small spur of this driving arrangement are shown in greater gear 92. With a supplemental drive 86, it is 10 detail in Figure 4. possible to move the final drive gears to their Figure 3 also shows the relative position of coast sides and to then effectively "over drive" bevel gears 88 and 90 which receive power from the main drive system to an extent necessary to an externally mounted AC motor 86 (Figures 1 remove backlash from a substantial portion of the and 2) for applying a driving component to a main drive system. This can be accomplished 15 pinion spur 92 which likewise is in meshing through the relatively efficient hypoid drive set (or engagement with the major gear 84 associated with a bevel gear set) of this invention but would with the work spindle 14. Additional details of this not be possible with a worm drive unit in the final arrangement are shown in Figures 5 and 6. drive system without providing a substantial As shown in Figure 6, the supplemental driving increase in power in the supplemental driving 20 system functions to apply a driving component to system. In this way, it is possible to remove the work spindle gear 84 in a direction of rotation backlash from the main drive train as cutting which is the same as the direction of rotation action takes place between the tool 10 and the imparted to the work spindle gear 84. The AC workpiece 16. Preferably, the motor 86 is motor 86 operates through a compliant mounted externally of the housing which con- 25 100 (which may comprise a known elastomeric or tains the work spindle assemblies so as to remove spring coupling) for absorbing any slight a heat source from the final drive system. differences in speed that may occur between the The drive train also includes a conventional two driving systems. With this driving system, the provision for axially feeding the hobbing tool supplemental drive serves primarily to drive the relative to the workpiece. This includes a feed 30 work spindle, while the hypoid gear set and spur 100 which is driven through a series of 82 serve to guide the precision rotation of the gears which receive power from the main drive work spindle. This not only eliminates backlash at train by way of the gears 106, 108, 110, 112, 114, the work spindle, but also provides for additional 116, 118, 120, 122, 124, and 126 and a clutch 128. driving force that may be needed for faster metal This provides for an adjustment of axial feed of 35 removal rates of the tool of the machine. the cutting tool as it rotates in timed relationship with a workpiece to thereby provide a desired Claims to teeth being formed on the work- piece. When a cutting cycle has been completed, 1. A hobbing machine having a drive train for the clutch 128 is disengaged to separate the drive 40 imparting rotation to a work spindle (14) while train from the tool, and a separate clutch 104 is feeding and rotating a hobbing tool (10) in timed then engaged to connect an AC motor 1 02 to drive relationship therewith, the feed screw 100 for rapidly returning the tool to a final drive system (78, 80, 82, 84) for the work its original position for starting a new cycle. spindle (14) comprising a hypoid or bevel pinion Figure 2 differs from Figure 1 by its inclusion of 45 (78) mounted to be rotated by the main drive train a differential mechanism 150 within the drive of the machine, the hypoid or bevel pinion (78) train previously described for Figure 1. Such an being in meshing engagement with a hypoid or inclusion of a differential mechanism is well bevel gear (80), respectively, for reducing the known in this art and provides for greater control speed of the drive train to the work spindle (14), in cutting helix angles on workpieces. In the 50 a spur pinion (82) and a spur gear (84) for Figure 1 embodiment, it is necessary to change further reducing speed of the drive train to the gears and gear ratios in order to adjust the helix work spindle, the spur pinion (82) being in a train angle on the workpiece. With the differential between the hypoid or bevel gear (78) and the provision of Figure 2, it is possible to adjust the spur gear (84), the spur gear (84) being oper- helix angle through an adjustment of the rota- 55 atively connected to the work spindle (14), and tional speed of the differential unit relative to the a supplemental driving system (88, 90, 92) input shaft of the main drive. This is done with the which includes a motor (86) for applying a differential change gears 151 which are driven by moment to the final drive system (78, 80, 82, 84) the D.C. motor 152. As with the previous embodi- for preventing backlash in that system. ment, a hypoid gear set (made up of hypoid 60 2. A hobbing machine according to Claim 1 pinion 78 and gear 80) and a spur gear set (made wherein the said hypoid or bevel pinion in the up of a spur pinion 82 and a spur gear 84) are final drive system for the work spindle (14) is a provided in the final drive assembly for the hypoid pinion (78) in meshing engagement with a workpiece spindle. hypoid gear (80). Figure 3 is a top plan view, partly in section, of 65 3. A machine according to Claim 1 or Claim 2 EP 0 094 392 B1 wherein the motor (86) is connected to a bevel Revendications pinion (88) and ring gear (90) which, in turn, tailler les impart a driving moment to a spur pinion (92) in 1. Machine a engrenages par genera- impartir meshing engagement with the spur gear (84) tion ayant un train d'entraTnement pour connected to the work spindle (14). s une rotation a une broche de travail 14, tout en alimentant et en faisant tourner un outil de taille le Patentanspruche des engrenages en relation dans temps avec lui, 84) 1. Abwalzfrasmaschine mit einem Antriebsge- un systeme d'entraTnement final (78, 80, 82, travail un triebe zum Verdrehen einer Werkstuckspindel (14) 10 pour la broche de (14) comprenant wahrend in zeitlicher Abhangigkeit hiervon ein pignon hypoTde ou conique (78) monte pour etre d'entratnement Abwalzwerkzeug (10) zugestellt und verdreht entratne en rotation par le train le hypoTde ou wird, principal de la machine, pignon de einem Endstufen- Antriebssystem (78, 80, 82, conique (78) etant en engagement prise avec 84) fur die Werkzeugspindel (14), umfassend ein w un engrenage hypoTde ou conique (80), respec- la vitesse du train d'entraT- Hypoid- Oder Kegelritzel (78), das zur Verdrehung tivement, pour reduire durch das Hauptantriebsgetriebe der Maschine nement a la broche de travail (14), droit (84) ist, wobei das Hypoid- oder Kegelritzel un pignon droit (82) et un engrenage gelagert train d'entratne- (78) mit einem Hypoid- oder Tellerrad (80) in pour reduire encore la vitesse du le droit (82) Eingriff steht, urn die Drehzahl des Antriebsgetrie- 20 ment a la broche de travail, pignon hypoTde ou bes zur Werkstuckspindel (14) zu verringern, etant dans un train entre I'engrenage einem Ritzel (82) und einem Stirnrad (84) zur conique (78) et I'engrenage droit (84), I'engrenage la broche weiteren Verringerung der Drehzahl des Antriebs- droit (84) etant activement connecte a getriebes zu der Werkstuckspindel, wobei das de travail (14), et Ritzel (82) in einem Getriebezug zwischen dem 25 un systeme d'entraTnement supplemental oder Kegelritzel (78) und dem Stirnrad (88, 90, 92) qui comprend un moteur (86) pour Hypoid- d'entraTnement (84) ist, wobei das Stirnrad (84) mit appliquer un moment au systeme angeordnet dans der Werkstuckspindel (14) gekuppelt ist, und final (78, 80, 82, 84) pour empecher le jeu ce einem zusatzlichen Antriebssystem (88, 90, 92), systeme. das einen Motor zum Aufbringen eines Momen- 30 2. Machine pour tailler les engrenages par 1 ledit tes auf das Endstufen- Antriebssystem umfaSt, generation selon la revendication ou dans le urn einen toten Gang in diesem System zu verhin- pignon hypoTde ou conique systeme dern. d'entraTnement final pour la broche de travail (14) (78) prise avec un 2. Abwalzf rasmaschine nach Anspruch 1 , wobei est un pignon hypoTde en das Hypoid- oder Kegelritzel in dem 35 engrenage hypoTde (80). besagte la Enstufen- Antriebssystem fur die Werkstuckspin- 3. Machine selon la revendication 1 ou del (14) ein Hypoidritzel (78) ist, das mit einem revendication 2 ou le moteur (86) est connecte a (80) kammt. un pignon conique (88) et a une couronne (90) ce Hypoidtellerrad d'entraTne- 3. Abwalzfrasmaschine nach Anspruch 1 oder 2, qui, a son tour, impartit un moment de wobei der Motor (86) mit einem Kegelritzel (88) 40 ment a un pignon droit (92) en engagement la und einem Tellerrad (90) verbunden ist, das sei- prise avec I'engrenage droit (84) connecte a nerseits ein Antriebsmoment auf ein Ritzel (92) broche de travail (14). iibertragt, das mit einem mit der Werkstuckspin- del (14) verbundenen Stirnrad (84) kammt. 45

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