US2246671A - Machine for shaping spur gears - Google Patents

Description

June 24, 1941. G. FISCHER MACHINE FOR SHAPING SPUR GEARS 4 Sheets-Sheet 1 Filed Aug. 24, 1938 Java/liar I Fzsc he 7' 0. By W, M

June 24, 1941. I G. FISCHER 2,246,671

MACHINE FOR SHAPING SPUR GEARS Filed Aug. 24, 1938 4 Sheets-Sheet 2 Fig. 2'

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G. FISCHER MACHINE FOR SHAPING SPUR GEARS Fil'ed Aug. 24, 1938 4 Sheets-Sheet 4 .712 21'6 n for: 6. E'scke Patented June 24', 1941 UNITED STATS T GFFECE Georg Fischer, Zollikon, Switzerland, assignor to Maag-Zahnriider und-Maschinen A. G., Zurich,

Switzerland Application August 24, 1938, Serial No. 226,415 In Germany August 28, 1937 (C1. Shh-9) 4 Claims.

My invention relates to a machine for shaping spur gears by means of a tool of the rack-type operating in accordance with the rolling process. More particularly, my invention relates to a machin of this kind in which the tool of the racktype is at least as long as the circumference of the spur gear to be out and, therefore, may cut a Whole gear within a single cycle of operation without any intervening indexing motions.

An object of my, invention is to provide a machine of this kind which is reliable and accurate in operation and may be readily set up for work of different pitch circle diameter. Further objects of my invention will appear from a description of a preferred embodiment thereof following hereinafter.

In the drawings,

Fig. 1 is a side view of the machine, partly in section,

Fig. 2 is an exploded view of the driving and controlling mechanism of the machine showing a plan view of some of the elements illustrated in Fig. 1,

Fig. 3 is a representation similar to that of Fig. 2 of a modified driving mechanism,

Fig. 4 is a section taken along line 4-4 of Fig. 1 showing different set ups for spur gears of different diameters to the left and to the right of the dash-dotted line, and

Fig. 5 shows some of the mechanism of Fig. 2 on an enlarged scale.

The bed I is provided with an upright having a swivel member rotatable about a horizontal axis provided with a guide extending within a vertical plane. On this guide there is slidingly mounted a ram 2 carrying the tool 5| of the rack-shaped type. The ram is reciprocated by means of a connection rod 3 and a crank t of the shaft 5. The shaft 5 is driven through gears "l, B, 9, It which are attached to the crank shaft '5 and two parallel gearshafts 6, II respectively. Moreover, on the shaft If there is fastened a bevel gear l2 engaging another bevel gear it which is driven by an electric motor l5 through a belt It.

A second drive serving to produce the rolling motion is derived from the shaft 6. For this purpose, a gear I6 is secured to this shaft and operates a gear [9 through a reduction gearing l1, l8 loosely mounted on the shaft H. The gear I9 drives a gear 23 through the intermediary of a shaft and gears 2| and 22. The gear 23 is attached to one end of a shaft 24, the other end of which carries a reversing gear. The reversing gear comprises two bevel gears 25 and El provided with clutch teeth 25 and freely rotatably mounted on the shaft 24. These bevel gears, which are suitably secured against axial displacement on the shaft 24, are in mesh with a common bevel gear 29. Between them, there is splined on shaft 24 a shiftable clutch sleeve 30 provided with a peripheral groove. Depending on whether the clutch sleeve is shifted to engagement with one or the other of the two bevel gears 26 and 27, the bevel gear 29 is rotated in one direction or the other. The bevel gear 29 drives meshing spur gears 3! and 32. The gear 32 is attached to a shaft or spindle 33 journalled in a bearing slidably mounted, as at 33 in a support 52 to permit said support to have adjustment in a direction transversely of said shaft and. the shaft suitably secured against axial displacement therein. Within this support, the shaft 33 is formed as a screw spindle 34 engaging a nut 35 which is attached to a slide 36. This slide 36 is movable on longitudinal guides ll, Figure 1, which are provided on the support 42 and extend horizontally at right angles to the crank shaft 5.

Therefore, when the shaft 33 is rotated in the one direction or the other, the slide 36 moves longitudinally on the support 42. The support 42 in its turn is slidably mounted on guides 13 which are provided on the bed I below the ram 2 and extend parallel to the crank shaft 5. A screw spindle 53 provided with a hand wheel 14 is journalled within a depending lug of the support 42 and secured against axial displacement therein. This screw spindle 53 engages a nut 15 attached to the bed I. Therefore, rotation of the hand wheel M causes the support 42 to be horizontally adjusted on the bed I in a direction parallel to the crank shaft 5.

The slide 38 is provided With a vertical bearing it having a comparatively large diameter for a purpose to be explained hereinafter. In this bearing, there is journalled a circular bearing member 3'! constituting a rotary work table or work spindle. This member has a conical bore accommodating a mandrel 38 attached therein. The downwardly projecting cylindrical end of this mandrel is journalled in a depending portion til of the slide 3t. On th mandrel there is attached a master spur gear i0 engaging a rack it. This rack and the rack M are located Within a common plane indicated by the dotted line 11 which extends parallel to the axis of the work spindle 3i and is preferably vertically disposed. This is the plane in which the tool 5| performs its reciprocatory cutting motion relative to the work spindle 31.

It is an important feature of my invention that the machine may be so set up as to cut gears of different diameters. For this purpose, the master gear it may be readily exchanged. When the operator wishes to take off the master gear ll] and to replace it by another one, he need only lift the spindle 3? out of its bearing it. Then, th master gear may be readily taken off the mandrel 38.

In order to avoid interference of the master gear with the removal of the work spindle, the diameter of the bearing member 3! is made larger than the largest gear that is to be cut on the machine.

In order that the rack ll will properly engage th master gear ie irrespective of the diameter thereof, the rack ll is transversely adjustable towards and away from the work spindle. The means for performing this adjustment comprise a wedge 43 more clearly shown in Fig. 4 which is inserted between the rack 45 and a vertical shoulder l8 provided on the support 42 and extending at an acute angle to the plane 11. The wedge =13 may be longitudinally adjusted by means of a set screw it. After adjustment the rack may be fixed by a screw 15 pressing the rack against a fixed stop it and by threaded bolts ll extending through slots of the wedge into threaded bores of the rack ii. By tightening the bolts 41 the wedge is firmly clamped between the rack s! and the shoulder 18.

The master gear lil must be so dimensioned that its pitch circle equals that of the gear to be cut. The number of its teeth, however, may be chosen as desired. For this reason, the same rack ll may be used together with various master gears 2-8 for cutting gears of different sizes and numbers of teeth. It is only necessary to adjust the rack ii to the proper distance from the axis of the spindle 3'! to eliminate lost motion between the rack and the master gear 46. Preferably, a plurality of wedges of different width are kept in store. Fig. 4 shows that a wedge 53 of small width is required in combination with a large master gear it, while a wide wedge 43 is required in connection with a small master gear til.

On the table 3? there is attached a chuck it including a mandrel 38 on which the blank 50 is attached. The rack-shaped tool 5| is preferably mounted on a swivel plate 52 which, in its turn, is mounted on a clapper plate (not shown) hinged about a horizontal pivot to the ram.

The pitch circle of the master gear is accurately coaxial with the pitch circle of the work gear rolling along the pitch line of the tool 5i. Therefore, the two gears ll! and 56 perform the same rolling motion. By adjustment of the hand wheel 14 and by the consequent transverse displacement of the support 42, the work piece fill and the tool 5| may be relatively adjusted to the proper radial distance without affecting the relative adjustment of the rack 41 and the master gear 40.

The mechanism for the manual and automatic control of the reversing gear 26, 2'! is illustrated in Figs. 2 and .3. The peripheral groove of the clutch sleeve 39 is engaged by a fork 28 pivotally mounted on a bracket which is suitably attached to the support Q2. The fork 28 forms one arm of a bell crank lever, the other arm of which is connected to a rod 83 which islongitudinallyshiftably mounted on the support 32 and extends parallel to the guide H and carries two adjustable stops M. These stops project into the path of a member 61 projecting from the longitudinal slide 36 and may be so adjusted as to be engaged by the member 67 when the slide 36 has completed its rolling motion. Owing to such engagement, the sleeve 3% is moved to its neutral position in which it engages neither of the gears 26 and 21 thus stopping the slide 38.

For starting the rolling motion of the slide the operator must shift a controlling lever 54 shown in Figs. 2 and 5 from its middle position 0 to one or the other of its end positions a and b.

This controlling lever 5 3 is mounted on the support 32 and is connected with a pinion 66 engaging rack teeth 65 provided on the rod 63. Therefore, the reversing gear is moved to one or the other of its operative positions when the controlling lever 54 is moved to its a-position or its b-position. Moreover, the controlling lever 5 is connected with a toothed sector engaging a pinion attached to a rotatable disc 55 provided with two opposite peripheral recesses 56. In the operative positions of the controlling lever 54 one or the other of these recesses 56 is in registry with one arm of a two-armed lever 57 cooperating with a press button 58 of a control switch 59 whereby the press button is released so as to automatically close a starter switch 62 controlling the motor it. The shaft H operated by the motor it drives the ram 2 as well as the reversing gear 25-28. 5

The operator first inserts a master gear it having the same pitch circle diameter as the gears to be out. Then, he must insert a proper wedge 63 and accurately adjust the same by means of the screw ii whereupon the screw 45 and the bolts 47 are tightened. Having thus completed the settings determining the proper rolling motion, the operator puts a blank on the chuck 49 and adjusts the support 52 by the hand wheel 14 to properly position the work blank so that the pitch line of the rack 51 will be tangent to the pitch circle of the gear to be cut.

After these adjustments have been performed, the operator moves the hand lever 54 from its neutral c-position to either the a-positon or the b-position depending on whether the slide is in its left end position or in its right end position. This causes the ram 2 to reciprocate and the slide 36 to start its motion, whereby the work blank 53 is caused to roll along the rack 5| the length of which is at least equal to the circumference of the pitch circle of the master gear and, therefore, equal to the length of the rack 4|.

When the motion of the slide 36 has started, the tool begins with its one end to cut out the teeth of the work piece. It will be recalled that, when the control lever 54 is shifted in one direct1on or the other, the reversing gear is at the same time shifted into one of its operative positions through the elements $6, $5, 63, 28 and 39, whereby the shaft 24 driven by the motor I5 is cooperatively connected with one of the two bevel gears 26, 2'5 which drives the shaft 33 and thus causes the slide 36 to move along the guides ll of the support 42 in a direction parallel to the rack it. Since the master gear 46 engages the rack 45 without any lost motion, it rolls along this rack with its entire periphery. The work piece 523 performs exactly the same motion as the master gear 40.

The engagement of the projection 61 with one or the other of the stops 64 occurs, when the master gear has completed one revolution and then causes the reversing gear to be shifted to its neutral position. At the same time, the rack teeth 55 shift the sector 66 and the controlling lever 54 to the c-position thus turning the disc 55 through a quarter of a revolution. This causes the lever 51 to be so turned as to press on the button 58 of the control switch 59 which, in its turn, causes the automatic starter 52 to stop the motor l5. Therefore, the entire machine stops. The work piece is now finished and may be removed and replaced with a new blank. Then, the control lever is shifted to b, whereupon another cycle of operation is initiated in which the rolling motion is performed in the opposite direction.

It may be desirable under certain conditions to operate on the same blank in two successive cycles, in the first cycle roughening the gear teeth with a comparatively high rolling speed and in the second cycle finishing the gear teeth with a slower rolling motion in the opposite direction.

For performing such an operation, I may modify the reversing gear as shown in Fig. 3. In this modification, the two bevel gears 26 and 2'! mesh with two different coaxially arranged bevel gears 29, 29. The gear 29 is connected for common rotation with the spur gear 3|. Similarly, the bevel gear 29' is connected with a spur gear 3|. These two spur gears have different numbers of teeth. They are in permanent engagement with two gears 32 and 32 rigidly attached to the shaft 33. Owing to this arrangement, the shaft or spindle 33 will operate the slide 36 at a higher speed when driven by engagement of the clutch sleeve 3|) with the bevel gear 21, but will operate the slide at a lower speed, when the sleeve engages the bevel gear 26. As the speed of reciprocation of the ram 2 is independent of the speed of the rolling motion of the blank 50 which is directly proportional to the number of revolutions of the shaft 33, the number of teeth of the gears 3|, 32 may be so selected as to obtain any desired number of cutting strokes per tooth.

As stated, the same rack 4| may be used for producing gears of different diameters and different numbers of teeth but that the master gear 4|] must be so chosen as to have the same pitch circle diameter as the gear to be cut. The adjustment of the rack 4| to proper engagement with the master gear is performed by means of a wedge 43 of a properly selected width. Obviously, however, the same wedge may be used in connection with master gears of different diameters provided that a bar of suitable width is interposed between the wedge and the shoulder 18.

My improved machine is equally well adapted to the manufacture of gears having straight teeth or gears having helical teeth. For cutting a helical gear it is only necessary to turn the swivel member 10 about its axis, whereby the guide of the ram 2 is positioned obliquely in accordance with the angle of the gear teeth.

The swivel plate 52, however, is preferably so adjusted as to hold the rack 5| parallel to the rack 4|, provided of course, that the tool rack 5| has oblique teeth corresponding to the helix angle of the gear to be cut.

I have not deemed it necessary to illustrate the exact location of the bearings of the various. gears and their shafts. However, the gears 9, I0, 2|, 22 and 23 are preferably so located as to be readily accessible and interchangeable. By exchanging these gears and selecting gears of proper numbers of teeth, the cutting speed and the rolling speed may be varied, as desired. Also, the gears 3|, 3| and 32, 32 may be interchangeable so as to enable the operator to modify the ratio of the rolling speeds of the slide 36 in both of its directions, if desired.

The reversing gear and its associated elements are preferably mounted on the support 42 while the gears transmitting motion from the motor IE to the ram and tothe shaft 24 are mounted in the upright of the bed I. To permit of a transverse adjustment of the support 42 on its guide 13, the shaft 24 is preferably splined in the gear 23 so as not to interfere with such transverse adjustment.

My invention is capable of numerous modifications which will readily occur to anyone skilled in the art. Thus, it is primarily the relative motion between the different elements that is of importance and the same relative motion may be obtained in a number of various ways by keeping one or the other element stationary, as desired, while permitting the other elements to move. Therefore, the invention is not limited to the exact details of the described embodiment 1 but is to be broadly interpreted in accordance with the claims following hereinafter.

What I claim is:

1. In a machine for shaping spur gears, a reciprocatory ram, a tool of the rack-type mounted on and extending transversely of the ram, a support, a rack mounted on said support in a common plane with said tool and coextensive therewith, a slide slida'bly mounted on the support to have movement parallelly of said rack, a work spindle journalled in said slide to rotate in a plane parallel to said tool and rack, a spur gear rotatable with said work spindle meshing with said rack, said tool having a length not less than the circumference of said spur gear, means for imparting reciprocatory movement to the ram and cutting motion to said tool in a plane parallelly of the axis of said work spindle, and means for mounting and adjusting said fixed rack towards and away from said work spindle, comprising a wedge engaged between the edge of the rack opposite the rack teeth and a wall portion of the support, a screw spindle connected to the wedge for longitudinally shifting said wedge, and means releasa-bly securing the wedge in adjusted position.

2. In a machine for shaping spur gears, a tool of the rack-type, a rack located in a common plane with said tool and coextensive therewith, a slide adapted to move parallel to said rack, a work spindle journalled in said slide and extending parallel to said plane, a spur gear attached to said work spindle and meshing with said rack, said too-l having a length not less than the circumference of said spur gear, means for producing a relative reciprocatory cutting motion between said tool and said work spindle within said plane, means for moving said slide including a screw spindle, driving means for said screw spindle, a reversing gear operatively connected to the driving means. adapted to connect said screw spindle to the driving means to rotate the screw spindle in one or the other direction and thereby move the slide in one or the other direction, a linkage manually operative for shifting said reversing gear from its normal neutral position to connect the screw spindle and slide to the driving means to be actuated in one or the other direction, and means operative at a predetermined movement of said slide to actuate said linkage to shift said reversing gear from its operative position into its neutral position and automatically disconnect the screw spindle and slide from the driving means and stop the operation thereof.

3. In a machine for shaping spur gears, the combination comprising a tool of the rack-type, a rack located in a common plane with said tool and coextensive therewith, a slide adapted to move parallel to said rack, a work spindle journalled in said slide and extending parallel to said plane, a spur gear attached to said work spindle and meshing with said rack, said tool having a length not less than the circumference of said spur gear, means for producing a relative reciprocatory cutting motion between said tool and said work spindle within said plane, and means for moving the slide in either direction including a motor, a motor switch, a screw spindle driven by said motor and driving said slide, a reversing gear interposed between said motor and said screw spindle, a linkage adapted to shift said reversing gear from its neutral position to one or the other of its operative positions and a connection between said linkage and said motor switch, whereby the motor is started when the reversing gear is moved from its neutral position and is stopped when the reversing gear is moved into its neutral position.

4. In a machine for shaping spur gears, a tool of the rack-type, a rack located in a common plane with said tool and coextensive therewith, a slide adapted to move parallel to said rack, a bearing in said slide, a bearing member journalled in said bearing having an annular flange at one end to engage and support the bearing member from the bearing to extend in a plane transversely of the rack, a Wonk carrying mandrel mounted in said bearing member, a spur gear attached to said work carrying mandrel and meshing with said rack to rotate the bearing member with the work mandrel by the movement of the slide longitudinally of the rack, said tool having a length not less than the circumference of said spur gear, the opening in the bearing and the lbearing member being of a diameter larger than the spur gear and permit removal of the bearing member with the spur gear as a unit from the bearing, means for producing a relative reciprocatory cutting motion between said tool and said Work spindle within said plane, means for adjusting said fixed rack towards and away from said work spindle, comprising a wedge disposed at the edge of the rack opposite the rack teeth and a fixed wall of the slide, and a screw spindle connected to and operative for longitu dinally shifting said wedge.

GEORG FISCHER.

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