US2751727A - Grinding head and grinding surface therefor - Google Patents

Description

June 26, 1956 w. E. McAFr-:E 2,751,727

GRINDING HEAD AND GRINDING SURFACE THEREFOR Filed Aug. 28, 1953 2 Sheets-Sneet l June 26, 1956 W. E. MCAFEE 2,751,727

GRINDING HEAD AND GRINDING SURFACE THEREFOR 2 Sheets-Sheet 2 Filed Aug. 28, 1953 1N VEN TOR. WALTER /Vcfe-E /YEY GRINDING HEAD AND GRINDING SURFACE THEREFOR Walter E. McAfee, Somerville, Mass., assiguor to I Jeavitt Machine Company, Grange, Mass., a corporation of Massachusetts Application August 28, 1953, Serial No. 378,339

7 Claims. (Cl. 51-190) This invention relates to valve grinding machines and more particularly to the grinding heads thereof. n

One object of this invention is an improved grinding head whose grinding surfaces are readily replaceable. To attain this object provision is made that the grinding surfaces be removably attachable to the grinding head.

Another object of this invention is the interposition of yieldable backing material between the grinding surfaces and the grinding head. The yieldable backing material is permanently attached to the grinding head to attain some of the advantages to be hereinafter pointed out. To attain still other advantages to be hereinafter pointed out, provision is made that the yieldable backing material be removably attacbable to the grinding head.

Another object of this invention is an improved grindin@ head whereby chattering is reduced to a minimum. To attain this object the grinding head is provided with a grinding surface along its working plane which is less than the surface of the grinding head at the working plane. Preferably, the grinding surface is an interrupted surface to form grinding sections which are spaced equidistant from each other. In the embodiment shown, the grinding sections are spaced equidistant from each other along the periphery of the grinding head, and more particularly as spaced from each other for an angular distance greater than the width of each grinding section.

A further object of this invention is a grinding head which will be quickly and easily adaptable to grind valves of any angularity. To attain this object the grinding head comprises a hub to be mounted on the valve grinding machine having shoes extending radially from the hub and grinding surfaces on the shoes. The shoes are shown as removable to serve the purposes of this invention, and as spaced radially equidistant from each other.

The accompanying drawing-s illustrate the preferred forms of my invention and show the invention as applied to a valve grinding head particularly adapted to grind globe valves and the specific details shown in the drawings are for that particular type of grinding head. In the drawing:

Fig. l is a plan View of the assembled device as viewed from the top;

Fig. 2 is a plan View of the assembled device as viewed from the bottom;

Fig. 3 is a sectional elevation taken on line lll-lll of Fig. l;

Fig. 4 is a sectional plan view taken on line IV-IV or Fig. 3;

Fig. 5 is a sectional elevation taken on line V-V of Fig. l;

nited States Patent Y 2,751,727 Patented June 26, 1956 the embodiment shown in the drawings, the shaft 3 has a constricted neck 5 and a reduced shaft portion 7 smaller in diameter than the main portion of the shaft 3 so as to present shoulder 9 upon which the hub 1 is adapted to abut. The reduced shaft portion 7 carries the key 1i which is enterable in the slot 13 of the hub 1 to permit the hub 1 to rotate with the shaft 3.

Extending inwardly from the bottom of the reduced shaft portion 7 is opening 16 leading into the threaded screw hole 15 which is adapted to accommodate the screw 17. The lock washer 19 abuts on shoulders 21 of the hub 1 and is tightened in place by screw 17 to xedly secure the hub 1 onto the shaft 3.

Extending radially from the hub 1 are the lugs 30. In the drawings three lugs 30 have been illustrated, but it is to be understood that any number more or less than tnree may be effectively used with this invention. The lugs 3e, as shown in the drawings, are spaced equidistant at 120 angles from each other. Each lug 30 has the hole 32. therein which is adapted to accommodate pin 34.

Shoes 4d are adapted to be mounted on the lugs 30 in any preferred or conventional manner. In the illustrated embodiment, each shoe 40 is provided with a recess 42 between the legs 44 to accommodate therein the lug 3d. The legs 44 are provided with pin holes 46 to accommodate the pin 34.

Each lug 30 is provided with keys 31 extending outwardly on either side thereof and adapted to enter the slots 41 on either side of the legs 44 of each shoe 40. The shoe 4d is attached to the lug 30 by sliding the slots 41 of the shoe 4d on the keys 31 of the lug 30 until the pin hole 3?. of the lug 30 and the pin holes 46 of the legs 44 are in alignment with each other. The pin 34 is then inserted in the pin holes 32 and 46 and secured in this position by the retaining rings 48 acting in the constricted necks 35 on either side of the pin 34.

Each shoe 4t) is provided with grinding surfaces illustrated in drawings as grinding strips 50 to form spaced grinding sections. These grinding surfaces 50 may be of any conventional abrasive and are shown as removably attached to the inclined working plane of each shoe 4t?. Each strip Si) may be attached to each shoe 40 in any desired and conventional manner. In the drawings, thisI attachment is accomplished by placing the ends of 51 of the strip Sil between the shoe legs 44 and the clamps 52 and tightening the screws 54 of the clamps 52 to hold the strip 50 secured on the shoe 40. The grinding strips 5i) are spaced from each other for an angular distance greater than the width of the grinding sections.

Resilient backing material 60, such as rubber or plastic, is interposed between each shoe 40 and the strip 50 on the working plane 89 of the shoe 40. This backing material 6d may be permanently attached to the inclined working plane gli of the shoe 40 (as shown in Fig. 6), or may be permanently attached to the strip 50 and placed on the shoe 4d with the strip 5t) (as shown in Fig. 7).

The advantage attained by using the embodiment of Fig. 7 is that a fresh yieldable backing piece is placed on the shoe 40 every time the grinding strip 50 is replaced. The advantage attained by using embodiment of Fig. 6 is that it is more economical.

ln operation, the hub 1 is inserted on the reduced shaft portion 7 until the hub 1 abuts the shoulders 9. The lock washer 19 is then placed in the opening 16 of the reduced shaft portion 7 until it abuts the shoulders 21 of the hub 1 and is fastened in that position by screw 17.

A shoe 40 having a working plane of a desired angularity is then mounted onto each of the lugs 30 in the manner described above. It will be understood, of course, that the shoes 4i) may be mounted on the lugs 30 before the hub 1 is attached onto the reduced shaft portion 7, if desired. The pin holes 46 and 32 of the i shoe legs 44 and each lug 30 respectively, are aligned and the pin 34 is inserted therein and locked securely by retaining rings 48 acting in the constricted necks 35 of the pin 34.

The grinding strips 50 are then placed on the working plane of each of the shoes 40. If desired, these grinding strips may be placed on each shoe 40 before the shoe -is mounted on the hub 1. In placing the grinding strips 50 on each of the shoes 40, the clamps 52 are opened by unscrewing the screws 54, the ends 5l are tucked between the shoe legs 44 and the clamps 52 are clamped down to securely retain the strip 50 on the shoe 4t? by tightening the screws 54. The same operation occurs whether the backing material 60 is permanently secured on the shoe 40 (as lshown in Fig. 6), or whether it is permanently secured to the strip 59 (as shown in Fig. 7), except that in the latter case the backing material 69 is attached with the strip 50.

The grinding head is then ready to grind a valve, such as the globe valve shown in dottedr lines in Fig. 3. The spaced grinding surfaces 50 will eliminate chattering and grind the valve evenly.

When the grinding strips 50 have been worn out they can he removed by unscrewing the screws 54, thus releasing the strips S0 from the clamping action of the clips 52, and a neu rgrinding Vstrip may be inserted as pointed out above.

When a valve having a particular angle has been ground, and the machine is to grind ay valve having a different angle, the shoes 40 are replaced with other shoes having an angular working plane corresponding to the angle of the new valve. This can be done without removing the hub 1.V Clamps 48 are removed and vthe pin 34 is slipped out of pinholes 32 and 46. The shoe is removed and the new shoe to be used is mounted on the lug 30 as pointed outy above. k

It will be observed that this arrangement permits the grinding surfaces to be replaced quickly, cheaply and conveniently, eliminates chattering because of the spaced grinding surfaces, and it permits a machine to grind valves of different angularity without radical modification of the machine.

I claim:

l. A grinding head for a globe valve grinding machine, said head comprising a central core mountable on a driving shaft for rotation therewith, a grinding shoe extending radially outwardly from and immovably aiiixed to the central core, said grinding shoe being defined by opposed side walls and an outermost end Vface presented in the working plane at that angle to the axis of rotation of the core required by the angle of the surface to be ground, and a relatively thin, flexible separably formed replaceable-abrasive strip having extension portions at its opposite ends bent rearwardly toembrace the side walls of the shoe to hold the intermediate portion of the strip in superimposed relation to and at the angle of saidY end face anda yieldable cushion interposed between said endface and said intermediate portion of the abrasive strip.

. 2. A grinding head as set forth in claim 1 wherein the cushion 1s tixedly attached to the inner face of the intermediate portion of the abrasive strip.

3. A grinding head as set forth in claim 1 wherein the cushion is iixedly attached tp the end face of the grinding shoe. y.

4. A grinding head for a globe valve grinding machine, said head comprising a central core mountable on a driving shaft for rotation therewith', a plurality of grinding shoes extending radially outwardly from and immovably aiiixed to the central core, each of said grinding shoes being defined by opposed side walls and an outermost end face presented in the working plane at that angle to the axis of rotation of the core required by the angle of the surface to be ground, the width of the end faces of the grinding shoes measured in the working plane, being less than the spacing therebetween in that plane, whereby chattering is minimized.

5. A grinding head for a globe valve grinding machine, said head comprising a central core mountable on a driving shaft for rotationtherewith, a plurality of grinding shoes extending radially outwardly from and immovably aixed to the central core, each of said grinding shoes being defined by opposed side wall-s and an outermost end face presented in the workingv plane at that angle tothe raxis of rotation of the core required by the angle of the surface to be ground, keach shoe having associated therewith a relatively thin, flexible, separably formed replaceable abrasive strip having extension portions at its opposite ends, bent rearwardly to embrace the side walls of the shoe to hold the intermediate portion of the strip inv superimposed relation to and at an angle of said end face, and a yieldable cushion interposed between said end face andsaid intermediate portion of the abrasive strip.

6. A grinding head as set forth in claim 5 wherein the yieldable cushions are each fixedly` secured to an end face of one of the grinding shoes.

7. For use with a grinding head for a globe valve grinding machine comprising a central core mountable on a driving shaft for rotation therewith, a grinding shoe eX- tending radially outwardly from and immovably afXed to the central core and defined by opposed side walls and an outermost end face presented in the working plane; of a relatively thin, liexible, separably formed abrasive strip having rearwardly bent extension portions at its opposite ends adaptedto embrace the sidewalls of the shoe to hold the intermediate portion of the strip in superimposed relation to said end face and a yieldable cushion interposed between said end `face and said intermediate l portion of the abrasive strip.

References Cited in the tile of this patent

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