METHOD FOR MAKING A SHAFT AND A GEAR

Abstract: Shafts (10) are cut to length from the leading end portion of an intermittently advancing piece of bar stock (13) and are transferred laterally therefrom and advanced step-by-step along a predetermined path (12). Each shaft dwells at a station (16) where a pre-gear forming operation (e.g., chamfering) is performed on the shaft, at a station (20) where a gear is formed on the shaft and at a station (25, 28) where a post-gear forming operation (e. g., heat treating or checking) is performed on the gear. All of the operations are performed while the shaft is held in a rotationally stationary position.

Description: METHOD FOR MAKING A SHAFT AND A GEAR BACKGROUND OF THE INVENTION This invention relates to a method of manufacturing a shaft and forming a gear- on the shaft. While the invention is not limited to any particular type of shaft or gear, the present method is particularly well suited for forming a spur gear or gear-type spline on one end portion of a shaft which is adapted for use as the drive shaft of a small electric motor. SUMMARY OF THE INVENTION The general aim of the present invention is to provide a new and improved manufacturing method which enables the shaft and the gear to be made on a highly automated basis and with comparatively simple and compact apparatus for transferring and holding the shaft during the various steps of the manufacturing cycle. A more detailed object of the invention is to achieve the foregoing by advancing the shaft automati¬ cally through stations where pre-gear forming, gear forming and post-gear forming operations are performed on the shaft with each operation being performed while the shaft is held rotationally stationary so as to avoid the need of providing apparatus for rotating the shaft and to enable simplification of the apparatus for transferring the shaft between the stations. Still another object is to provide a method in which shafts are successively cut to length from the leading end portion of an elongated piece of inter¬ mittently movable bar stock and then are automatically advanced through the pre-forming, the forming and the post-forming stations. The invention also resides in the operations carried out in the various stations and in the unique manner by which the operations are perfor ed. These and other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a typical shaft and gear adapted to be formed by the new and improved method of the present invention. Fig. 2 is a top plan view which schematically illustrates exemplary apparatus for carrying out the method of the invention. Fig. 3 is a front elevational view taken along the line 3-3 of Fig. 2 and shows the gear forming apparatus. Fig. 4 is a side elevational view of the gear forming apparatus as taken along the line 4-4 of Fig. 3. DESCRIPTION OF THE INVENTION The present invention involves a method of manu¬ facturing a shaft 10 and forming a gear 11 on the shaft. In the present instance, the shaft is σylind- rical and is of relatively small diameter (e.g., 1/4 ■ inch) . The gear 11 is formed on one end portion of the shaft and is in the form of a straight spur gear or a gear-type spline. The outside diameter of the gear is approximately the same as the diameter of 5 the shaft. A shaft of this type is commonly used as the drive shaft of a small electric motor. In accordance with the present invention, the shaft 10 and the gear 11 are formed by a unique method which enables the manufacture to be carried out on a 10 virtually fully automated basis and with relatively simple and compact material handling and transfer apparatus. The invention is particularly characterized by the fact that the shaft 10 is held in a rotationally stationary position while pre-gear forming, gear form- 15. ing and post-gear forming operations are performed on the shaft. To carry out the method, transfer means 12 are provided for advancing successive shafts 10 step-by- step along a predetermined path -and through several 20 stations,where various operations are performed on the shafts while the latter dwell. The transfer means may take various forms such as a rotary index table having clamps for holding the shafts and adapted to advance the shafts around a circular path. Alterna- 25 tively, the transfer means may be a reciprocating walking beam adapted to transfer the shafts along a straight path through the various stations and asso¬ ciated with means for clamping the shafts in the stations. For purposes of simplicity, the transfer 30 means 12 has been shown schematically as being a conveyor adapted to be advanced with step-by-step motion along a straight path and having clamps for securely holding the shafts. In keeping with the invention, the individual 35 shafts 10 are cut to length from an elongated piece of bar stock 13. As shown in Fig . 2 , the bar stock extends transversely to the rear side of the conveyor 12 and is adapted to be advanced lengthwise and for- wardly with a step-by-step motion. During each advance , the leading end portion of the bar stock advances forwardly across the conveyor 12 and then its leading end is stopped by a transversely adjust¬ able positive stopping device 14 . The conveyor 12 then clamps the shaft. Thereafter , a saw 15 moves toward and cuts through the bar stock 13 to sever the leading end portion therefrom and cut a shaft 10 to length . The saw 15* then retracts , and the conveyor advances the shaft laterally away from the bar stock and into the first operating station 16. At the first station 16 , a pre-gear forming opera¬ tion is performed on the shaft 10 . In the present instance , the pre-gear ' forming operation consis ts of chamfering both ends of the shaft 10 as indicated at 17 in order to remove burrs and sharp edges from the ends . The chamf ring is performed by two transversely movable heads 18 each having a chamfering tool 19 adapted to be advanced into engagement with the end of the shaft and adapted to be advanced into engage¬ ment with the end of the shaft and adapted to be rotated to form the chamfer 17 on the rotationally stationary shaft. It will be appreciated that another pre-gear forming operation (e . g . , keyway cutting) may be per¬ formed on the shaft at the station 16 or at a station immediately downstream of the station 16. After the pre-gear forming operations have been performed, the shaft 10 is advanced by the conveyor 12 into a gear forming station 20 . At this station, the gear 11 is formed on the shaft 10 while the latter is held in a rotationally stationary position . The gear may be formed by different ones of the machines disclosed in our co-pending application Serial No . 041,680, filed May 23, 1979, entitled Shape Generation By Orbiting A Rotating Cutter and assigned to the assignee of the present invention. The gear forming machine which has been illustrated is a hobbing machine 21 having a transversely movable slide 22. A head 23 is mounted to rotate on the slide about an axis which is aligned with the axis of the shaft 10. A hob 24 is supported on the head at a location offset from the axis of the head and is adapted to be rotated about its own axis. To form the gear 11, the slide 22 is moved transversely while the head 23 and the hob 24 are rotated around their respec¬ tive axes. This causes the hob 24 to move along and - orbit around the shaft 10 and, at the same time, to turn about its own axis to form the gear 11 on the rotationally stationary shaft. Reference may be had to the aforementioned co-pending application for a more detailed disclosure of the construction and opera¬ tion of the hobbing machine 21. Another hobbing machine 21 ' may be located in a station downstream of the hobbing machine 21. The hobbing machine 21' may be used if the machine 21 is down for repair or if a gear of a different type or size is to be formed on the shaft 10. One or more post-gear forming operations are per¬ formed after the gear 11 has been hobbed. Herein, the first post operation involves heat treating the gear 11 at a station 25 downstream from the hobbing machine 21 ■ . The heat treating is effected by a transversely movable induction heater 26 having a coil 27 which is adapted to telescope over and inductively heat the gear 11 when the shaft 10 dwells in the station 25 and the heater is moved forwardly. Means (not shown) also may be provided in the station 25 for quenching the gear after the heater has been retracted. Consist¬ ent with the invention, the shaft 10 is held in a rota- _...O.;PΓ ' tionally stationary position during the heating and quenching steps . At the next downstream station 28 , the newly formed gear 11 is checked to determine if the gear meets designated standards . The checking is effected by apparatus 29 which is disclosed in our co-pending application Serial No . 153 , 599 , filed May 27 , 1980 , entitled Method And Apparatus For Checking a Gear (Attorney ' s Docket No . 08129 ) and assigned to the assignee of the present invention. Such apparatus includes a master gear 30 which is adapted to be brought into meshing engagement with the gear 11 while the shaft 10 is held ro tationally . The master gear 30 " orbits around the gear 11 much in the same manner as the hob 24 and, at the same time, rotates freely around its own axis so as to irol.l around the stationary gear 11. During this movement, the center distance between the gear 11 and the master gear 30 is gauged by an electrical detecting device (not shown) which produces a signal indicative as to whether the gear is acceptable . Our last-mentioned application may be referred to for a more detailed disclosure of the construction and operation of the gear checking apparatus 29 . At the final station 31, the shaft 10 is removed from the conveyor 13 by a transversely movable ejection mechanism 32 which pushes the shaft into a downwardly inclined chute 33. A shaft with an acceptable gear 11 proceeds down the chute to a collection area while a shaft with a non-acceptable gear falls out of the chute through a trap door 34 . The door is opened automatic¬ ally in response to the checker 29 producing a signal that a non-acceptable gear has been produced and is proceeding down the line . From the foregoing, it will be apparent that the present invention brings to the art a new and improved ethod for making a shaft 10 and a gear 11 where all of the operations may be performed without need of rotating the shaft. As a result, the apparatus for performing the method does not require rotary chucks or the like and may be incorporated in a relatively simple, inexpensive and compact package.

Claims: -8- CLAIMS We claim: 1. A method of manufacturing a shaft and forming a gear on the shaft, said method compris ing the steps of, intermittently advancing a shaft of predetermined length along a predetermined path through a succession of stations and permitting the shaft to dwell in each of said stations , performing a pre-gear forming operation on said shaft when the latter dwells in one of said stations , performing a gear forming operation on said shaft when the latter dwells in a succeeding station thereby to form a gear on said shaft, and performing a post-gear forming operation on said gear when said shaft dwells in a subsequent station, all of said operations being performed while holding said shaft against rotation about its own axis . 2. A method of manufacturing a shaft and forming a gear on the shaft, said method comprising, inter¬ mittently advancing an elongated piece of bar stock in a lengthwise direction, cutting through the lead- ing end portion of the bar stock when the latter dwells thereby to sever a shaft of predetermined length from the bar stock, advancing the shaft step-by-step along a predetermined path through a succession of stations and permitting the shaft to dwell in each of said stations, performing a pre-gear forming operation on said shaft when the latter dwells in one of said stations, performing a gear forming operation on said shaft when the latter dwells in a succeeding station thereby to form a gear on said shaft, and performing a post-gear forming operation on said gear when said shaft dwells in a subsequent station, all of said operations being performed while holding said shaft against rotation about its own axis. 3. A method as defined in claim 2 in which said pre-gear forming operation comprises the formation of a chamfer on at least one end of said shaft. 4. A method as defined in either of claims 2 or 3 in which said gear forming operation is performed by hobbing said shaft. 5. A method as defined in any of claims 2, 3 or 4 in which said post-gear forming operation comprises heat treating said gear. 6. A method as defined in claim 5 further includ¬ ing the step of performing a second post-gear forming operation on said gear when the latter subsequently dwells after being heat treated, said second operation comprising the step of checking said gear while hold¬ ing said shaft against rotation about its own axis and while orbiting a master gear about said axis and in rolling contact with said gear. 7. A method as defined in any of claims 2, 3 or 4 in which said post-gear forming operation comprises checking said gear while orbiting a master gear about said axis and in rolling contact with said gear. 8. A method as defined in claim 2 in which said shaft is advanced laterally of said bar stock after being severed there-from and is advanced along a straight path through said stations. 9. A method of manufacturing a shaft and forming a gear on one end portion of the shaft, said method comprising, intermittently advancing an elongated piece of bar stock in a lengthwise direction, cutting through the leading end portion of the bar stock when the latter dwells thereby to sever a shaft of predeter¬ mined length from the bar stock, advancing the shaft laterally away from the bar stock and step-by-step along a straight path through a succession of stations and permitting the shaft to dwell in each of said stations, performing chamfering operations on the ends of said shaft when the latter dwells in one of said stations, performing a gear hobbing operation on one end portion of said shaft when the latter dwells in a subsequent station thereby to form a gear on said one end portion of said shaft, performing a heat treating operation on said gear when the shaft dwells in a subsequent station, and performing a gear checking operation on said gear when the shaft dwells in a subsequent station, all of said operations being performed while holding said shaft against rotation about its own axis.

Inventors: FRANSSON G, HAUG E, JOHNSON S
Applicants: BARBER COLMAN CO
Application year: 1981
Main classification: B21K1
IPC codes: B23P13, B23P15