US2995068A - Hobbing machines - Google Patents

Description

Aug. 8, 1961 J. A. MILLS HOBBING MACHINES s Shets-Sheet 1 Filed Feb. 10, 1958 llllllllllml llqull lrlll 6 Sheets-Sheet 2 Filed Feb. 10, 1958 Aug. 8, 1961 J. A. MILLS HOBBING MACHINES Filed Feb. 10, 1958 6 Sheets-Sheet 3 8- 1961 J. A. MILLS 2,995,068

HOBBING MACHINES Filed Feb. 10, 1958 6 Sheets-Sheet 4 Aug. 8, 1961 J. A. MILLS HOBBING MACHINES 6 Sheets-Sheet 5 Filed Feb. 10, 1958 Aug. 8, 1961 J. A. MILLS HOBBING MACHINES 6 Sheets-Sheet 6 Filed Feb. 10, 1958 United States Patent 2,995,068 HOBBING MACHINES John Alfred Mills, Blaydon-on-Tyne, England, assignor to Churchill Gear Machines Limited, Blaydon-on-Tyne, England Filed Feb. 10, 1958, Ser. No. 714L234 Claims priority, application Great Britain Feb. 15, 1957 3 Claims. (Cl. 90-1) The invention has reference to hobbing machines.

A hobbing machine comprises essentially a hob or tooth cutting tool, a work-head on which the gear blank is deposited, a tail stock which bears centrally on the. blank deposited on the work-head, means for feeding the workhead relative to the hob and means for driving the hob and the work-head in timed relationship so that the hob cuts the teeth in the gear blank to form a hobbed gear.

The present invention has for its object to provide means whereby gear blanks conveyed to a bobbing machine are transferred from a feed table or conveyor deposited on the work-head and when the hob has cut the teeth therein, lifted and deposited on the table or conveyor.

The invention has for its further object to provide improved means whereby the blanks are fed to the transfer means and, after the teeth have been hobbed thereon, re-

'turned to the table or conveyor and finally delivered therefrom.

According to the present invention a hobbing machine is provided with an automatically acting transfer unit comprising a vertically arranged hydraulic cylinder and ram assembly, a horizontally arranged hydraulic cylinder and ram assembly projecting laterally from and carried by the vertical ram, hydraulically operated means whereby said vertical ram with the horizontal assembly can be given a partial rotary movement about a vertical axis, a pair of pivotally mounted cooperating jaws mounted to move with the vertical ram and actuated by the horizontal ram and valve means controlling the axial movement of the rams and the rotary movement of the vertical ram and horizontal assembly carried thereby, the construction and arrangement being such that by the operation of the valve means in timed sequence the jaws are operated to clamp therebetween a gear blank on a feed table, conveyor or the like, the vertical ram raised to lift the blank, then given a partial rotation to bring the blank over the work-head and then lowered to deposit the blank on the work-head whereon the jaws are released, such cycle of operations being then reversed to transfer the hobbed gear back to the table, conveyor or the like.

The invention further consists in a bobbing machine having a table to receive a multiplicity of gear blanks, conveyor mechanism by which the gear blanks are fed one at a time to a position opposite the hobbing machine, an automatically acting transfer unit as set forth in the preceding paragraph to transfer each blank in turn to the work-head where the blank is hobbed and thereafter transfer the hobbed gear to the table, said conveyor mechanism comprising an endless chain passed over two sprocket wheels, means for driving the chain step by step and a series of arms carried by the chain and which engage the blanks and hobbed gears, and a discharge or unloading chute to which the hobbed gears are delivered and down which they roll.

The invention further consists in the provision in a hobbing machine as set forth in the preceding paragraph but one of a conveyor and combined electrical and hydraulic control system comprising an arrangement of microswitches, one of which is operated by the rotation of the ram and cylinder assemblies about a vertical axis and the other by conveyor indexing means, solenoids energised on the closing of said switches, a valve controlled by the solenoids, an arrangement of sequence valves operated by built up pressure so that the various operations of the transfer unit are effected automatically in the order set forth, and a further micro-switch operated by the jaws and controlling a further solenoid-operated valve by which an hydraulic cylinder and ram indexes the conveyor.

The invention will now be described with reference to the annexed drawings wherein:

FIGURE 1 is an end elevation of a hobbing machine in accordance with the invention;

FIGURE 2 is a plan view thereof but omitting the tailstock;

FIGURE 3 is a sectional elevation of the transfer unit;

FIGURE 4 is a plan View thereof;

FIGURE 5 is a section on the line 5-5 of FIGURE 3;

FIGURE 6 is a section through the back plate of the transfer unit, the section being on the line 66 of FIG- URE 4;

FIGURE 7 shows diagrammatically such part of the hydraulic system and electrical system as is necessary for the understanding of the invention;

FIGURE 8 is an elevation of the conveyor; and

FIGURE 9 is a plan view thereof.

In the drawings A designates the hob or cutting tool, B designates the! work-head on which the gear blank is deposited, C designates the tailstock, D designates gear blanks and E is a pump driven by a motor F by which pressure fluid is supplied to the hydraulic system of the machine.

The improved hobbing machine is provided with a table 10 extending transversely of the front thereof. Mounted on vertical spindles 11 located towards the two ends of the table are two sprocket wheels 12 around which is passed an endless chain 13. The chain is omitted in FIGURE 8. At spaced distances apart are outwardly extending fingers 14 carried by the chain, only two of which are shown, each finger having an inwardly projecting toe 15.

Mounted on the table is an hydraulic ram and cylinder assembly 16, the cylinder having a projecting spring loaded driving member 17 which is arranged to engage with each toe 15 in turn so that the chain with the fingers is moved step by step at each reciprocation of the cylinder. The said member operates when moved in one direction and is inoperative when moved in the reverse direction.

Pressure fluid to this cylinder is controlled by a fourway valve 18 which in turn is controlled by a solenoid 19 the coil of which is energised on the closing of a microswitch 20 by the opening of the jaws hereafter described. When the jaws close the switch opens to de-energise the solenoid so that the valve returns to its initial position whereon the fluid in the cylinder can return to a sump, the valve being reversed by a spring 20a.

The table is provided with a shallow depression 21 to receive and guide the blanks D as they are carried along by the said fingers 14 and at one end the depression leads to a chute 23 which extends below the table and is inclined downwards to the discharge end thereof.

To the front, of the bobbing machine and above the table is secured an hydraulically operated transfer unit. This unit comprises an upper cylindrical casing 24 and a lower cylindrical casing 25 anchored to a back plate 25a secured to the hobbing machine, the upper casing having a cover 24a. Extending through the two cylindrical casings is a cylindrical column or ram 26. The upper and lower casings provide bearings for both axially sliding and rotation of the vertical column or ram therein. The column is provided with an upper axial bore 27 and carries at its upper end a piston 28. The upper casing forms an upper annular chamber 29 and a lower annular chamber 30, the upper chamber and cover therefor being provided with ports 31 .and 32 respectively through which pressure fluid under the control of a valve 324 is admitted to act on either side of the piston and is thereafter exhausted, said valve being operated by two solenoids.

The said column is provided with a cylindrical lateral horizontal extension 33 in which works a piston or ram 34 which carries an outwardly extending piston rod 35. The lower annular chamber 30 is provided with a port 36 through which pressure fluid can be admitted thereto and exhausted therefrom under the control of said valve 32a and a sequence or pressure operated valve 32b. Said chamber is placed in communicationwith the bore 27 in the column by passages 37, the upper end of the bore being sealed by a screw threaded member 37a by which the piston 28 is secured to the column. The bore 27 above the lateral cylindrical extension communicates with a passage 38 in the wall of the said extension and this passage is in communication with the lateral cylinder on the outer side of the piston 34 therein. The cylindrical extension on the other side of this piston communicates with a bore 39 in the lower part of the column which bore, at its lower end, constitutes a port 39a for the admission and exhaust of pressure fluid under the control of said valve 32a. v I

The lower end of the column is secured by a key 40 to an enclosing sleeve 41 provided with a vertical vane 42 which works in an annular chamber 43 formed in the lower cylindrical casing 25 and provided with a fixed vertical abutment 44 secured to the casing by a key 44a. The column can slide vertically relative to the sleeve and. can be rotated by the action of the sleeve. The chamber on each side of the abutment is provided with inlet and exhaust ports 45 and 46, see FIGURE 5, to which pressure fluid is admitted and exhausted through valve 32a, sequence valves 32c and 32d and valve 32a which latter is operated by two solenoids.

The aforesaid spindle 35 carries a bracket formed by twosuperimposed lugs 47 and 48 and an intermediate ofl-setlug 48a each of which is provided with a pin 49. A plate 50 secured to the column extends laterally below said bracket and carries a pivot pin 51 on which are mounted two (to-operating jaws 52 and 53 each of which is provided with a slot 521; and 53'a'respectively in which works one of said pins 49.

The meansfor controlling automatically the operation of the improved hobbin'g machine embodies a microswitch 54 which is closed when the cylinder 16 is at the end of its indexing stroke, the closing of this switch energising one of the solenoids of both of the valves 32a and 32a so that pressure fluid is directed to initiate the fi'rst'seri'es of operations terminating in the blank being positioned over the work he'ad. A second micro-switch 57 is closed automatically as hereafter described and, when closed, completes the circuit of the other solenoid of valve 32a which is moved to initiate th'e'first of a series of operations commencing in placing the blank on the work-head. On completionof the normal bobbing cycle the breaking of a micro-switch, not shown by the operation of the bobbing machine begins a series of operations terminating in the bobbed gear being deposited on the conveyor.

The back plate 25a of the transfer unit is provided with a pair of trips 60, only one of which is shown. When the column is rotated one or the other of said trips cooperates with a spring loaded roller 61 on the end of one arm of a bell crank lever 62 the other arm of which operates through a pin 63 the aforesaid second microswitch 57. Said switch is in a circuit of one of the solenoids controlling the valve 32a which controls the admission and exhaust of pressure fluid to effect the downward vertical movement of the column, 'lateral movement of the piston rod 35'andthe operation of the clamping jaws.

In describing the operation of the machine it will be assumed that gear blanks are located between each pair of outwardly extending fingers 14. That is, the machine is loaded with its full complement of blanks. It will be further assumed that the transfer unit has deposited a hobbed gear on the table and that the cylinder 16 has been indexed to operate the micro-switch 54. The valve admit pressure fluid through port 31. The fluid acting. on the underside of the piston 28 raises the vertical col umn with the lateral extension andthe blank carried by the jaws. r I

Thereafter the sequence valve 32d opens to admitpressure fluid through port 45 or 46 to act on one side of the vertical vane 42 to cause the column to rotate through about about its vertical axis so that the blank is now directly over the work-head B. Just prior to the completion of the partial rotary movement a trip 60 carried by the column closes micro-switch 57 whereon valve 32a controlling the vertical movement of the column isoperated so that pressure fluid is supplied through port 32 to lower the column and deposit the blank on the Workhead. Thereafter fluid acting on sequence valve 32b isadmitted through port 36 to act on and force inwardly the piston 34. The jaws are thereby separated to'release the blank. The blank is then bobbed by the normal machine cycle.

On the completing of the'hobbing cycle a microswitch, not shown, is closed by the hobbing machine to 'energise the other solenoid of valve 32a, this valve being thereby reversed so that pressure fluid is admitted through 'port 39a and bore 39 to force outwardly the piston 34. This results in the ho'bbed gear being again gripped by the jaws. Pressure then builds up in sequence valve 320 and pressure fluid thereby admitted through port 31 to raise the column with the hobbed gear carried by the jaws. Pressure then builds up in sequence valve 32d which then admits pressure fluid to act on the other side of the vane so that the column is rotated to bring the hobbedgear over thetable. A second trip 60 functions to close microswitch 57 which reverses valve 32a so that pressure fluid is now admitted through port 32 to act on the force downwards the piston 28. The gear is thereby lowered on to the table. When pressure builds up in sequence valve 32b pressure fluid is admitted thereby through port 36, bore 27 and passage 38 to act on the outer face of the piston 34. The latter is thereby forced inwards to cause the jaws to open. The opening of the jaws results in micro-switch 20 being closed and this in turn results in solenoid 19 being energised to reverse valve 18 so that fluid under pressure is admitted to cylinder 16. The movement of the cylinder-is transmitted to the chain which moves the hobbed gear along the table and indexes the next blank.

After the indexing stroke of cylinder 16 micro-switch 54 is closed causing valves 32a and 32d to be reversed. This'causes the jaws to close releasing micro switch 20 which de-e'nergizes and thus allows pressufe'fl'uid to be admitted to the other side of cylinder 16 toenable it to return to its start position.

The machine has now commenced the aforesaid cycle of operations to hob the next blank.

It will'be seen that the hobbed gears are fed by the fingers so that they are delivered one at a time to the chute 23 down which they roll "and by which they are delivered. Thus the machine may he fed with a 'm'ul'tiplicity of blanks and thereafter each trans-mum -is fed to thefw'ork h'ea'd and wnentne'gremaave been thereu returned to "the table andnn-atly delivered t?) the discharge chute, all such operations being automatically efiected in timed relationship.

What I claim is:

1. A hobbing machine provided with an automatically acting transfer unit comprising a vertically arranged hydraulic cylinder and ram assembly, a horizontally arranged hydraulic cylinder and ram assembly projecting laterally from and carried by the vertical ram, hydraulically operated means to impart to said vertical ram with the horizontal assembly a partial rotary movement about a vertical axis, a pair of pivotally mounted cooperating j-aws mounted to move with the vertical ram and actuated by the horizontal ram, valve means controlling the axial movement of the rams and the rotary movement of the vertical ram and horizontal assembly carried thereby, and a feed table or conveyor for the gear blanks and hobbed gears, the construction and arrangement being such that by the operation of the valve means in timed sequence the jaws are operated to clamp therebetweena gear blank on a feed table or conveyor, the vertical ram raised to lift the blank, then given a partial rotation to bring the blank over the work-head and then lowered to deposit the blank on the work-head whereon the jaws are released, such cycle of operations being then reversed to transfer the hobbed gear back to the table or conveyor.

2. A hobbing machine provided with an automatically acting transfer unit comprising a pair of vertically aligned cylinders, a vertical ram located in said cylinders, said ram having an upper axial bore closed at its upper end and a lower axial bore, a piston carried by the upper end of the ram, the upper cylinder having ports by which pressure fluid can be admitted to act on both faces of the piston, a laterally extending cylinder carried by the ram, a horizontal piston working in the laterally extending cylinder, the lateral cylinder on one side of the piston communicating with the lower bore and on the other side of the piston communicating with the upper bore, a bracket carried by the vertical ram, a pair of jaws pivotally mounted on the bracket, means by which the axial movement of the horizontal piston in one direction positively moves the jaws towards each other and axial movement in the other direction positively opens the said jaws, a vane rotatable with the vertical ram and working in the lower cylinder, an abutment dividing the lower cylinder to form a chamber on each side of the vane, the lower cylinder having ports communicating with said chambers, and valve means by which pressure fluid can be admitted via the lower biore to the lateral cylinder to force outwardly the lateral piston and thereby cause the jaws to grip a gear blank positioned therebet-ween on a conveyor, valve means to thereafter admit pressure fluid below the piston of the ram to raise the latter together with jaws and gear blank carried thereby, valve means to thereafter admit pressure fluid to act on one side of said vane to impart a partial rotary movement to the vertical ram about its vertical axis together with the lateral piston and cylinder and jaws, valve means to admit pressure fluid to the top of the piston so that the ram together with the lateral piston and cylinder together with the jaws are moved downwards to deposit the gear blank on the workhead, and valve means to admit pressure fluid via the upper bore to the lateral cylinder to force its piston inwardly so that the jaws are opened to release the gear blank and means whereby, after the blank has been hobbed the aforesaid cycle is reversed to transfer the hobbed blank to the conveyor.

3. In a hobbing machine as claimed in claim 1 means for indexing the conveyor and a combined electrical and hydraulic control system comprising an arrangement of micro-switches, one of which is operated by the rotation of the ram and cylinder assemblies about a vertical axis and the other by the conveyor indexing means, solenoids energised on the closing of said switches, a valve controlled by the solenoids, an arrangement of sequence valves operated by built up pres-sure so that the various operations of the transfer unit are efiected automatically in the order set forth, and a further micro-switch operated by the jaws and controlling a further solenoidoperated valve by which an hydraulic cylinder and ram indexes the conveyor.

References Cited in the file of this patent UNITED STATES PATENTS 536,341 Hansen Mar. 26, 1895 565,285 Larsen Aug. 4, 1896 1,179,510 Edwards Apr. 18, 1916 1,210,237 Walker et al Dec. 26, 1916 2,325,164 Goodwin July 27, 1943 2,382,013 King Aug. 14, 1945 2,570,660 Gamble Oct. 9, 1951 FOREIGN PATENTS 18,839 Great Britain Aug. 16, 1909

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