US1973329A - Indexing or dividing mechanism for machine tools - Google Patents

Description

sept. l1, 1934. R. J. BULLQWS 1,973,329

INDEXING OR DIVIDING MEGHANISM FOR MACHINE TOOLS Filed April 25, `193.2 2 sheets-sheet 1 Sept. 11, 1934. R 1 BULLOWS 1,973,329

INDEXING OR DIVIDING MECHANISM FOR MACHINE TOOLS Filed April 23. 1952 2 Sheets-Sheet 2 LL//OWS Patented Sept. 11, 1934 4 INDEXINGv OR DIVIDING MECHANISM-FOR MACHINE TOOLS ,l

'e Richard John Bllow's, Handsworth, '-Birmingham, England, assignor to The Gear Grinding Company Limited, England Handsworth, Birmingham,

ApplicationApril` 23, 1932, serial No. 697,174

In Great Britain July 1V, 1931 2 claims. 4(c1. 519-216) This invention` has for its object to provide improved indexing mechanisms, such as` are employed in machines for cutting or grinding gear Wheel teeth, splined shafts and for other analogous purposes. Y

,The invention comprises the combination With a rotatable, notched, toothed or other like member connected with the work piece, of means for imposing a, constantly acting torque on the said l0 member, a pawl or its equivalent acting on vthe said member, and means for moving the pawl or its equivalentintoand outlof action.-

In particular the inventioncomprises the combination withthe rotatable member, of a iiuid operated device for'exerting therequired torque.

Further the invention comprises the combination Withlthe means for actuating the paWl or the like,gof aV valve for regulating the supply of fluid tothe torque device. Y

Inthe two-accompanying sheets'ofexplanatory draWings:-

Figure` 1 is a sectionalvfront elevation of a portion of a, machine provided with the invention and adapted for grinding spline shafts, gear g5 wheels or like bodies by means of grinding wheels shaped to the-contours of the surfaces to be ground, and Figure 2 is a sectional end view of the machine.

Figure 3 .is a vsectional end View illustrating a uid operated motor for exerting torque on the Worin-and Figure 4 is a sectional front elevation ofl a valve for controlling the fluid supplied to the motor. i ,v j

Figure 5 is a plan of the mechanism for actuat- 35 ing the pawl which engages a notched dividing plate on the headstock of the machine.

The machine illustrated is adapted more particularly for use in the grinding of splined shafts, gear Wheels and like bodies, by means of a grind- L0 ing wheel having its periphery shaped exactly to correspond with the contour of the faces to be ground, the grinding being eiected by moving the Work relatively to the rotating Wheel in a direction parallel With the axis of the Work, and l5 the axis of the wheel being situated at right angles to the axis of the Work. Alternatively the Wheel may be moved parallel with the axis of a stationary work piece.

The Work piece, or a spindle carrying the same, 5.0 is carried at one end by the hollow spindle a of a headstock containing the dividing mechanism. This mechanism in accordance with the present invention, consists of a ratchet Wheel b secured to the spindle, the pitch of the teeth of the ratchet Wheel corresponding exactly to the angular movements requiredto begiven to the spindle after each grinding operation. The spindle is held against movement during the grinding operation by the engagement therewith of a pivoted pawl C. Thel pavvl is held in engagement with the ratchet wheel by a plunger d which may be loaded by a spring 13 or Weight, andthe extent to which the kpavvlr can be pressed into engagement with the ratchetvvheel is limited by a xed abutment e.

In the headstock is arranged a multicylinder fluid motor f lin each cylinder of which is a piston, allV the pistons being arrangedto act on a common cranky provided on one end of a spindle h which is connected With the spindle a by gear Wheels lc.` The spindle h may be adapted in any convenient manner to control the supply 'of motor uid, (usually oil) to and from the various cylinders of the motor. The fluid is conveyed by a pipe l from a pump or other convenient source to ,a valve o to be hereinafter described, and after passing through this valve it flows along a pipe m (Figures 3 and 4) to a passage n Which communicates by'means of a pipe o With the housing or bearing of the spindle h.

Exhaust fluid from' the motor passes back to the pump or other sourcethrough a pipe or passage p.

By means ofthefluid motor, a constant torque is exerted lon the 'spindle a which torque is resisted by the paWlc when the latter engages'a tooth oflthe ratchetlb. `Under the combined and opposing'actions of the motor and pawl, the spindle a is effectively held against accidentalmovement during the grinding operation.

t After' each `operation, the required Vangular movement is given to the spindle a for bringing another part of the Work piece under the action of the grinding Wheel by momentarily releasing the pawl c from the ratchet Wheel. This is effected in the example illustrated by means ofV a rod q acted on by a spring r and connected through the valve v, a bell crank lever s and link t to the pawl. Upward movement is given to the rod q for releasing the pawl by means of a lever u which at one end is supported on a xed stop w. Coaxially with the lever u is pivoted a hand lever a: carrying a detent y controlled in one direction by a spring e, and in the other direction by, for example, a peg 2 rigid with a lug on a slidable slotted bar 6 Which is connected at one end to the lever :n and is hereinafter referred to. Referring to Figure l, movement of the lower end of the hand lever .r to the left causes the detent y to engage a shoulder 3 on the lever u and move the lever u in the direction for lifting the rod q Vrc and releasing the pawl c. As soon as the detent y passes the shoulder 3 the rod is free to return under the action of the spring r and thereby reengage the pawl c with the ratchet. During the opposite movement of the hand lever :c towards the right, the detent y rocks idly on the lever a: against the spring e and so enters into re-engagement with the shoulder 3 without moving the lever u. y

Actuation of the lever :c may be effected by hand or automatically. Automatic operation is effected as follows in the example illustrated. The heaclstock containing the `spindle a is caraV ried on a slide 4 which is reciprocated by any convenient means on the xed bed 5 of the machine. At one side of the slide is carried the slotted bar 6 which as previously indicated is vcennected at one end to the lever a: and is controlled by a spring 7. And on the bar is secured Aan adjustable abutment 8 which can be engaged by a stop 9 on a lever 10 pivoted on an adjacent fixed part of the machine. This lever can be moved out of action when required by a link 11. Assuming the stop 9 to be in its active position as shown, movement of the'slide to the right brings the abutment 8 into contact with the stop. As the bar 6 is now held by the' stop, continued movement of the slide (which carries the lever m) to the right causes that lever to move towards the left and give an upward'movement to the rod q for releasing the pawl c as above described. During the return movement of the slide the part 8 is carried away from the stop 9 and the bar 6 and lever :a are returned by the spring '7,

As soon as the pawl is` released or disengaged from the ratchet b,, the spindle a is rotated by the torque exerted on it by the motor f. The actuation ofthe rod q is only momentary, and therefore immediately after the pawl has been released, it is allowed to return in readiness Afor arresting the ratchet when the next tooth of the ratchet reaches the pawl. y f

` It has already beenmentioned that the motor f exerts a constant torque on the spindle a.` This .implies that pressure .fluid is constantly acting on the motor, although iiuid does not pass through the motor when the latter is at rest. While the motor is in motion it s desirable and necessary to provide it with an ample supply of pressure fluid, in order that it may operate quickly; But it is not desirable to allow the pawl to re-engage the ratchet when the latter is rotating at high speed; otherwise a detrimental blow will be given to the pawl each time it reengages the ratchet. I therefore employ the valve v to regulate the supply of fluid to the motor. When the pawl is in action as shown in Figure 2, the valve restricts the fluid vpassage between the pipes l m but does not completely intercept the passage. On raising the rod q, the valve is caused to open the passage and allow a free flow of fluid to the motor. As the rod q returns immediately after the pawl has been released, the free fiow of fluid is only of brief duration and the valve is caused to restrict the flow and 4so prevent an excessive blow being given to the pawl when the latter encounters the next tooth on the ratchet.

Preferably the valve v is formed with a groove 14 for controlling the passage between the parts l, m and the part '16 containing the valve is formed with holes 17 which are narrower at one end than at the other (see Figure 2) the narrow end only being exposed to the groove when the pawl is in full engagement with the ratchet.

The invention is not limited to the example abo-ve described as subordinate 'details can be varied to suit different requirements. Also the invention is not limited to use on machines for shaping gear wheel teeth or splined shafts, as it may be applied to any other analogous uses in which indexing mechanisms are employed.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:-

l. In indexing or dividing mechanisms for machine tools, the combination witha :rotatable toothed member' connected with the workpiece, of a fluid operated device for imposing a unidirectional constantly acting torque on the said member, a stop acting on the said member, means for moving the stop into and out of action',4 and a valve operatively associated Awith saidfm'eans for regulating the supply of fluid to the saidv device substantially as described.

' 2. In indexing or dividing mechanisms as claimed in claim 1, the combination of a rotatable spindle, a ratchet secured to the spindle, a pivoted pawl engaging the ratchet, a fluid motor, gear wheels interconnecting the motor and spin dle, a spring controlled slidable rod for actuating the pawl,l a valve also `actuated by the rod, the said valve `serving to control the fluid supply to the motor, a pair of levers for operating the rod, and a Vdetent on one of the levers for effecting unidirectional engagement of the levers, substantially as described.

RICHARD' JOHN `BULLovvs.

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