US2301610A - Trimmer mechanism for grinding machines - Google Patents

Description

Nov. 10, 1942. 5. ca. BRADY TRIMMER MECHANISM FOR GRINDING MACHINES Filed March 5, 1941 5 Sheets-Sheet l v INVENTOR SAMUEL G-BRADY BY; 2' 5 Z A TTORNE YS Nov. 10, 1942. s. a. BRADY TRIMMER MECHANISM FOR GRINDING MACHINES Filed larch 3, 1941 3 Sheets-Sheet 2 INVENTOR SQMUEL G. BRADY MW $424M ATTORNEYS Nov. 10, 1942. s. G. BRADY 2,301,610

TRIMMER mncmmxsm FOR GRINDING MACHINES Filed March 3, 1941 5 Sheets-Sheet 5 INVENTOR I SAMUEL G. BRADY BMW/WW A TTORNE YS Patented Nov. 10, 1942 UNITED STATE-S'PATENT OFFICE TRIMMER MECHANISM FOR GRINDING MACHINES Samuel G. Brady, Detroit, Mich., assignor to The Gear Grinding Machine Company, Hamtramck, Mich., a corporation of Michigan Application March 3, 1941, Serial No. 381,584

4 Claims.

The invention relates to trimmer mechanisms for formed grinder wheels and has more particular reference to a construction adapted to trim tangent curves.

In the trimming of formed grinder wheels for use in the grinding of gears, splines, etc., the opposite sides of the wheel are fashioned by separate diamond trimming points. It is also usual to trim the peripheral edge of the wheel by another trimming point, but the several curves formed by these points are separate from each other. With certain classes of work it is desirable to trim contours having tangent curves, but difficulty is experienced in adjusting the trimmers to produce this result. Thus, if there is a slight misalignment of the adjacent curves, this will create a groove or ridge in the work being ground, which is highly objectionable.

It is one of the objects of the instant invention to obtain a construction of trimming mechanism capable of trimming difficult curves which are exactly tangent to each other,

It is a further object to trim such curves by a single trimming point.

Still further, it is an object to associate this single trimming point with other trimmers for producing further tangent or substantially tangent curves in the trimmed contour.

With these objects in view, the invention consists in the construction as hereinafter set forth. In the drawings:

Fig, 1 is a side elevation of my improved trim mechanism, partly shown in central longitudinal section;

Fig. 2 is a plan view, some are in section;

Fig. 3 is an end elevation;

Fig. 4 is a diagram indicating the different centers of movement for the single trimming point and their relation to each other and to the contour to be trimmed; and

Fig. 5 is a cross section on line While my improved trimmer is various uses, I

tangent portions of which 5-5 of Fig. 1.

shall specifically describe an ar rangement for trimming grinder wheels used in grinding splines.

As shown in Fig. 4, A is a portion of a shaft or other member provided with a series of splines B in indexed relation to each other and wi h intermediate grooves C. The strength of such a structure for transmitting torque stresses is greatly augmented if the splines are formed with curved fillets at the roots thereof. Also, the fillets of adjacent splines should be tangent to the surface forming the bottom of the groove between applicable to.

. a member pivctally secured adjacent splines, as well as being tangent to the side faces of the splines. To accomplish this result, I have devised a mechanism in which a single trimming point is alternately movable about a plurality of different centers and is locked from movement about one center during its movement about another center. This in sures the exact tangency of the curves concentric with their respective centers.

More in detail, D is the base for my improved trimming mechanism which is mounted upon the work carriage E of a grinding machine and is secured thereto by suitable means such as a depending flange D at one side of the carriage, the hook D for engaging a groove in the carriage, and a nut D engaging a threaded shank of said hook to clamp the same. The base D is further secured to the carriage by clamping bolts D The base D has an upwardly extending portion D on which is mounted a vertically extending member F. To the front face of the member F is pivctally secured a member G to swing in a vertical transverse plane. The pivotal connection is preferably formed by a pivot pin F extending through a longitudinal bore in the member F and having a tapered forward end portion F for engaging a correspondingly tapered bushing member G in the member G. This insures the holding of the member G in a fixed plane while permitting its pivotal movement in said plane. The member G is further provided with a rearwardly extending lug G This lug is arranged between adjustable stop members F and F preferably screws, engaging upwardly extending lugs F and F on opposite sides of the member F. The arrangement is such that by adjusting the screws F F the amount of movement permitted to the lug G and consequently the amount of angular movement of the member G on the pivot F may be limited.

H is a member vertically adjustably secured to the front face of the member G, which latter is provided with a grooved guideway G engaging a spline H on the members H. H are clamping bolts for securing the member H in different positions of adjustment, which bolts engage laterally projecting ears H and pass through vertical slots G in cars G on the member G. I is to the front face of the member H by means of the pivot pin I having the tapering rear portion I which engages ccrresponding tapering bushing H in the member H. The member H is also provided with an annular groove H which surrounds and is diamond trimming point J is movable about the 7 axis of the pivot pin I to describe an arc of a radius equal to the distance between said point and said axis. Also, by swinging the members I and 111 about the axis of the pivot F, the diamond point will describe an arc of a radius equal to the distance between the same and said axis. It

will also be understood that as the diamond point J is located between the axes of the pivot pins I and F, the arcs traced by movement about their respective axes will be of reverse curvature, but tangent to each other. However, it is necessary that movement around one axis must be prevented during movement about the other axis, as otherwise an irregular curve would be traced which would be non-concentric with either axis.

For performing the specific trimming operation of a grinder wheel for grinding a spline shaft as illustrated in Fig. a, movement of the trimming point about the axis of the pin I is used for trimming the root fillet grinding portion of the grinder wheel. n the other hand, movement of the diamond point about the axis of the pin F is used for grinding the portion of the grinder wheel which forms the bottom of the groove C. The length of the arc concentric with the axis F is limited by the stops F and F and it is also necessary to limit the length of the arc concentric to the axis I so that the curve will be tangent to the portions of the grinder wheel which grind the side faces of the splines. These side faces are trimmed by separate diamond point trimmers, but as such trimming mechanism is similar to that which has heretofore been used for the same purpose, it is not necessary to describe the same in the instant application. However, as above stated, it is essential that the length of the arc described about the axis I should be limited.

Also, it is necessary to provide locking means for holding the member I against pivotal movement while the trimmer point is describing the are about the axis F. As illustrated, the looking means for the member I comprises a locking bolt or pin K which is arranged in a longitudinal bore centrally within the member J. The rear end of the pin K has a cylindrical portion K of smaller diameter, terminating in a tapering portion K The portion K engages a correspondingly shaped bushing K in the member H. This bushing is so located that when engaged by the pin K, the diamond point will be in a plane that is common to both axes I and F. In other words, the diamond is located at the point of tangency of the two curves, respectively, described about the axes I and F. The pin K in its unlocked position is also utilized. for limiting the arcuate movement of the member I about the axis of the pin I. In this it cooperates with a pair of adjustable stops L and L, preferably formed by screws engaging threaded apertures in the member H and extending into the annular groove H to be substantially tangent thereto. Thus, when the member I is turned about the pivot I in either direction from its locked position, the portion K of the pin K will contact with one or the other of the stops L and L, which will prevent further rotation. The belt or pin K may be operated by a lever M which is fulcrumed at M on the member I and extends inward through a recess therein intersecting with the bore which holds the bolt. The inner end of the lever M has a pin portion M extending into a recess in the bolt with sufficient clearance to permit a relative angular movement of the lever. A spring K normally urges the bolt toward its locking position, and the lever M retracts the bolt against the tension of this spring. i

The grinder wheel to be trimmed is indicated in dotted lines at N (Figs. 1 and 4) and is mounted on a suitable support (not shown). To facilitate setting of the trimming mechanism, the member F is laterally adjustably secured to the portion D of the member D by clamping bolts 0. These bolts pass through slotted bearings in the base of the member F, and a spline O on this base engaging a transverse groove in the portion D prevents movement in any other direction. Screws 0 engaging ears 0 projecting upwardly from opposite sides of the portion D and bearing against the base portion of the member F form a means for adjusting the same. For adjusting the member G about the pivot F, I have provided a screw P engaging a threaded bearing in an upwardly projecting ear P on the member, F. The inner end of this screw has a loose swivel engagement With a pin P rotatively engaging a recess in the lug G extending outwardly therefrom. The opposite end of the screw P is provided with a crank handle P and by turning this crank handle, the member G may be moved in either direction until arrested by the stops F and F Operation In setting the trimming device for trimming a grinder wheel, the shank J of the diamond point trimmer J is adjusted in the member J so as to locate this point a predetermined distance from the axis of the pin I. This will determine the radius of the curve for. forming the root fillet B of the spline B. The member H is then adjusted on the member G, so as to space the axes of the pins I and F a predetermined distance from each other. This may be accomplished by loosening the bolts H sliding the spline H in the groove G and then again tightening the bolts. The spacing between these axes should be equal to the length of radius for the curve B plus the desired length of radius for forming the curve of the bottom B of the recess C. After such adjustment, the table E is moved to bring the diamond point into the vertical axial plane of the grinder wheel N, the member I being in its locked position. The grinder wheel is then adjusted downward into engagement with the trimming point, after which the crank handle I is turned to swing the members G, H, I and J about the axis of the pin F. This will trim the periphery of the grinder wheel to a concave contour, corresponding to the bottom B of the space between splines. When the trimmer point has completed its operation and is at one end of its movement, as for instance limited by the stop F the leverN is actuated to withdraw the locking bolt K, and this same lever is then used to swing the members I and J about the axis of the pin I. The starting point of this movement is the end of the arc B so that the curve B will be tangent thereto. The limit of swinging movement about the pin I is determined by the adjustment of the stop L, and this is so set that the curve will be substantially tangent to the side B of the spline B, which is above the root fillet B. The same operation is performed when the trimmer point is at the opposite end of its movement about the axis of the pivot F so as to trim the grinder wheel for forming the root fillet of an adjacent spline.

It will be understood that the portions of th grinder wheel which grind the sides B of the splines B are trimmed by independent trimmers. Therefore, the original setting of the stops F F and L, L is such as to bring the arcs B substantially tangent to these sides. Exact tangency is not essential "as long as the arcs B do not undercut the grinder wheel at their point of juncture with the sides B It is therefore preferable to adjust the stops W, F so as to permit a slight over movement around the axis of the pin F which will space the centers of the two fillets B slightly farther apart. This will avoid the formation of any undercut in the grinder wheel between the portions trimmed by the diiTerent trimmers.

What I claim as my invention is:

1. In a trimming mechanism, the combination with a trimmer point, of an arm carrying said point angularly movably about a pivot on one side thereof, a second arm to which said first arm is pivoted angularly movable about a pivot on the opposite side of said point, releasable means for normally locking said arms to each other when relatively positioned to hold said point in a plane common to both said pivots during the angular movement of the last mentioned arm about its pivot, an adjustable stop for limiting the movement of said last mentioned arm while permitting said first mentioned arm when unlocked to move angularly about its pivot, and an adjustable stop for limiting the angular movement of said first mentioned arm.

2. In a trimming mechanism, the combination with a trimmer point, of an arm carrying said point angularly movable about a pivot on one side thereof, a second arm to which said first arm is pivoted angularly movable about a pivot on the opposite side of said point, a bolt for normally locking said arms to each other when relatively positioned to hold said point in a plane common to both said pivots during angular movement of the last-mentioned arm about the last-mentioned pivot, an adjustable stop for limiting the movement of said last-mentioned arm, a lever for releasing said bolt constituting a handle for moving said first-mentioned arm angularly about said first-mentioned pivot, and an adjustable stop for limiting the angular movement of said first-mentioned arm.

3. In a trimming mechanism, the combination with a trimmer point, of an arm carrying said point angularly movable about a pivot on one side thereof, a second arm to which said first arm is pivoted angularly movable about a pivot on the opposite side of said point, a bolt for normally locking said arms to each other when relatively positioned to hold said point in a plane common to both of said pivots, a screw for actuating said last-mentioned arm about said last-mentioned pivot and for holding the same in each position of adjustment, said screw being provided with a crank handle for rapid rotation of the same,

, spaced adjustable stops for limiting tht movement in opposite directions of said last-mentioned arm, a lever for releasing said bolt when said lastmentioned arm is in contact with one or the other of said stops, said lever constituting a handle for rotating said first-mentioned arm about said first-mentioned pivot, and spaced adjustable stops for limiting the angular movement of said first-mentioned arm.

l. A trimming mechanism comprising a frame, a member pivotally supported on said frame, a second member secured to said first member to be radially adjustable in relation to the pivot, a third member pivotally secured to said second member, a trimmer point carried by said third member and radially adjustable in relation to the second pivotal connection, a locking belt for normally holding said third and second members relativcly positioned to hold said trimmer point in a plane common to both pivots, a screw for angularly adjusting said first member on said frame and for holding the same in each position of adjustment, said screw being swiveled to said firstmentioned member and provided with a crank handle for rapid rotation of the same, spaced screw stops for limiting the movement of said first member on said frame in opposite directions, a lever for releasing said bolt when said first member is in contact with either one of said stops, said lever constituting a handle for rotating said third member about its pivot, and spaced screw stops for limiting angular movement of said third member in opposite directions.

SAMUEL G. BRADY.

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