US3669089A - Swing arm for holding a dressing device - Google Patents

Abstract

A swing arm for holding a dressing device is adapted for mounting on a column or base portion of a machine tool. The swinging end of the arm is disposed to hold a threaded dressing member while the arm is swung in an arc around a pivot shaft. The pivot shaft retains a pivot joint which includes a roller thrust bearing disposed between the fixed and the movable member with a spring-type washer urging the fixed and the rotatable member together in a determined frictional relationship. An O-ring is seated in a groove formed at the roller raceway so as to seal the thrust bearing as well as provide a dust seal and vibration dampener.

Description

nited States Patent Swenson [4 1 June 13, 1972 [54] SWING ARM FOR HOLDING A 3,233,949 2/1966 Rieman ..308/3 A DRESSING DEVICE 1,760,800 5/1930 Wambsgans ..287/101 [72] inventor: Henry F. Swenson, 22 Holmehill Lane, p H Whitehead Roseland, NJ. 07068 Attorney-Ralph R. Roberts [22] Filed. Dec. 16, 1970 ABSTRACT [21] 98654 A swing arm for holding a dressing device is adapted for mounting on a column or base portion of a machine tool. The [52] U.S.Cl. ..l25/llR, 287/101 swinging end of the arm is disposed to hold a threaded 51 Im. c1 ..B24b 53/12 dressing member while the arm is swung in an arc around a s8 1 Field of Search 125/1 1, 1 1 A; 287/101; pivot Shaft The Pivot Shaft retains pivotioim which includes 30 3 A a roller thrust bearing disposed between the fixed and the movable member with a spring-type washer urging the fixed 56] References Cited and the rotatable member together in a determined frictional relationship. An O-ring is seated in a groove formed at the UNITED STATES PATENIS roller raceway so as to seal the thrust bearing as well as provide a dust seal and vibration dampener. 1,266,707 5/1918 Olson ..l25/ll A Spracklen ..287/101 6 Claim, 3 Drawing Figures I PATENTEDJUN 1 a man INVENT OR. HENRY E SWENSO/V BY 7 m AGENT SWING FOR HOLDING A DRESSING DEVICE CROSS REFERENCE TO A RELATED APPLICATION The swing arm of this application is shown as a preferred dressing tool holder used on and'with a center-hole grinder as shown and described in U.S. Pat. No. 3,548,545 which issued Dec. 22, 1970.

BACKGROUND OF THE INVENTION 1. Field of the Invention With reference to the classification of art as established in the U.S. Patent Office this invention pertains to the class entitled, Stone Working," and more particularly to the subclass therein entitled grinding wheel dressing."

2 Description of the Prior Art Dressing devices for truing the face or faces of grinding wheels usually. require the movement of a dressing device such as a diamond dresser across the face of a grinding wheel. In order that this dressing device be maintained in a true predetermined pl'ane providing thedesired facing action, the movement of the movable arm must be precisely controlled. In the swing arm shown in the preferred embodiment a springloaded pivot joint permits the dressing device to be selectively moved in a precise and prescribed are around the pivot joint in a vibration dampened manner. An example of a swinging arm device is seen in U.S. Pat. No. Re. 26,920 which issued June 23, 1970 to Parapetti. In this patent and others showing like devices there is provided elaborate arm construction disposed to provide movement control means which attempt to prevent unwanted and excessive vibration of the dressing medium when and as it is moved over the face of a grinding wheel to effect dressing of said wheel to a determined faced condition. In the dressing device shown in the .Parapetti patent and in many similar devices the arm construction is extremely elaborate and expensive and often does not provide the dampening effect necessary to provide a true dressing or shaping of the grinding wheel. I I

In the present invention there is provided a simple swing arm of two-piece construction wherein a novel pivoted assembly providesa simple joint of substantial strength and having a low friction. The pivot joint additionally provides a selective, dampening action which is provided by an adjustably tightened cup-shaped spring washer which permits the movable arm to be swung while being restrained by a desired frictional restriction.

SUMMARY OF THE INVENTION swing action of the movable arm.

It is a further object of this invention to provide, and it does provide, a swing arm for holding a dressing device wherein the fixed arm is attachable in an adjustable manner to a portion of a machine tool and in which the swinging arm portion is rotatably carried by an anti-frictional pivot joint, said swing arm having a threaded aperture at its outer end adapted to receive and adjustably retain a dressing holder having a threaded outer body.

The swing arm of this invention includes a support member which is removably mounted to the machine tool. A swing member has its outer end provided with a threaded aperture disposed to receive and retain a grinding wheel dressing means such as a diamond dressing point. The pivot joint between the support and swing member provides an anti-friction arrangement in which a roller thrust bearing is mounted between the members and sealed from grit and dust by means of an O-ring. The head of the pivot pin is retained by a ball bearing while the other end of the pivot pin and the whole joint is maintained in a determined tensioned and frictional restraint by a cup-shaped spring washer which is adjustably tightened to provide the desired frictional resistance against vibration and rotation.

In addition to the above summary the following disclosure is detailed to insure adequacy and aid in understanding of the invention. This disclosure, however, is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how it may later be disguised by variations in form or additions of further improvements. For this reason there has been chosen a specific embodiment of the swing arm as adopted for use in grinding wheel dressing and showing a preferred means for mounting the arm to the base or other fixed portion of a machine tool.

This specific embodiment has been chosen for the purposes of illustration and description as shown in the accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represents a sectional side view showing the preferred construction and assembly of the swing arm of this invention;

FIG. 2 represents a plan view of the arm of FIG. 1, the view taken on the line 22 of FIG. 1, and

FIG. 3 represents, in an enlarged sectional view, a fragmentary portion of the roller thrust bearing and the means for mounting an O-ring to provide the shielding for the thrust bearing necessary to prevent the penetration of dirt, dust or other contaminants into the rollers of the thrust bearing.

In the following description and in the claims various details will be identified by specific names for convenience; these names, however, are intended to be generic in their application. Corresponding reference characters refer to like members throughout the several figures of the drawing.

The drawing accompanying, and forming part of, this specification discloses certain details of construction for the purpose of explanation of the broader aspects of the invention, but it should be understood that structural details may be modified in various respects without departure from the concept and principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in particular to FIGS. 1 through 3, it is to be noted that a fixed member 10 is formed with an elongated slot 12 extending longitudinally through a substantial portion of the member. This slot is shouldered to receive and retain the head 14 of a socket head cap screw 16 seen in phantom outline in FIG. 1. This arm 10 has its right end reduced in thickness to provide an upper face portion 18 of a flat determined extent. In the middle of this face portion and at right angles thereto is formed an aperture 20 of determined size which is disposed to receive the outer diameter of the shank of a headed pivot pin 22.

A swinging arm member 30 is shown partly in section in FIG. 1 and includes a threaded aperture 32 formed through the right or distal end of the swing member 30. The left or pivoted end of this member is reduced slightly in thickness to provide a flat and parallel surface 34 adapted to support one of the race members of a roller thrust bearing 38. This thrust bearing is of a conventional construction and has two facing race members which are identified as 40 and 42. These race members are usually hardened and ground steel designed to support the thrust or load of a plurality of rollers 44 in a customary manner. These rollers are shown as carried in a cage 46 which is normally provided with a roller thrust bearing. A rubber O-ring 50 is sized to seat in chamfered shoulders 52 and 54 which are formed on the outer facing edges of members 40 and 42 so as to provide a smooth retaining seat for the O-ring when the bearing has been mounted in its usual rotating condition. In its assembled condition as seen in FIG. 3, the O-RING 50 is in a slightly stretched condition when it is 54. The snug fit of the O-ring provides a dust and dirt shield and at the same time it provides a small degree of restriction to the relative movement of race members 40 and 42 to one another.

The chamfered shoulders 52 and 54 are specially formed on members 40 and 42 so that in its assembled condition a determined groove is provided. The groove shoulders are preferably quite smooth so that the O-ring may slide on these surfaces without attrition of the O-ring and to reduce the ability of dust, dirt and wet slurry to enter the bearing.

Arm 30 has an aperture 60 formed therein which is sized to provide a rotative guide and retention of the shank of pivot pin 22. A shouldered recess 62 is formed on the underside of arm 30 and is made concentric with aperture 60. This recess receives and retains the outer race of a ball bearing 64. This bearing 64 is contemplated to be a combination radial and thrust bearing of conventional configuration. The inner race of the bearing 64 receives the shank of the pivot pin 22 and also accepts and retains the thrust load exerted by the head of the pivot pin.

Pivot pin 22 is headed at one end which as seen in FIG. 1 is the lower end. In the preferred embodiment, a threaded aperture 66-is formed axially through pin 22 and may have threads per inch for receiving a one-quarter inch screw. A cup-spring washer 70 has a determined outer diameter and an inner diameter whose aperture is adapted to receive the head 72 of an oval-headed screw 74 and to seat this head in the inner aperture of the washer 70. The threaded shank of the screw 74 is mounted in and retained in the threaded aperture 66 in the pivot shaft 22. A set screw 76 is shown as also mounted in the threaded hole 66 and is accessible through the head end of the pivot shaft 22 so as to be rotatably tightened to lock the screw 74 in its adjusted position.

USE AND OPERATION OF THE SWING ARM Preferably member 10 is brought to a support member 80 as seen in phantom outline in FIG. 1. This support member is provided with a taped or threaded hole 82 adapted to receive the threaded end of cap screw 16. The member 10 when screw 16 is tightened is brought into a determined clamped or retained relationship with body 80. A wedge member 84 may be mounted in a groove and hole in member 80, or any other suitable type of adjusting support block or wedge member may be provided so that member 10 may be slid back and forth and tilted to provide a desired angular relationship of member 10 to the block. This also determines the angular relationship of threaded hole 32 to the face of the grinding wheel to be dressed. This grinding wheel being of any conventional configuration and mounting has not been shown. With member 10 in.a locked condition in a desirable angle to and on the body member 80, the arm 30 may be now moved around the pivot pin 22 by manipulation of the outer end of the arm 30. The screw 72 is rotated in or out to provide a determined tension or load on the thrust bearing 38 and the ball bearing 64. The tension or load is increased in response to the degree of flatening of the cup-shaped washer 70. A grinding wheel dressing device is contemplated as being carried by a threaded shank 86 shown in phantom outline in FIG. 1. The dressing device is adjusted as it is rotated in or out in the threaded aperture 32 and is moved forwardly or backwardly the amount necessary or desired to bring the dressing end of the member in way of the face of the grinding wheel to be dressed.

The roller bearing 38 provides a smooth anti-friction support of member 30 by member 10. The bearing 64 insures that the member 30 as it is rotated around the head of the pinion member 22 moves with an equal amount of restraint. As the thrust load developed by the tightening of spring 70 places a like load upon the bearing 64 it is desirable that the bearing 64 be a ball bearing having properties adapted to accept and maintain at all angles or rotation the determined amount of thrust provided by the spring 70. The screw 72 is adjusted to provide the desired degree of bias or load on the bearings 38 and 64 so that as the arm 30 is moved to a determined dressing position it will stay at this position while the dressing device carried by shank 86 is rotated forward and back to the desired dressing condition whereupon the arm 30 is swung in an arc to dress the face of the grinding wheel in the desired manner.

The swing arm of this invention provides'a simple means of providing an anti-friction joint having a high thrust capacity as provided by means of a pre-loaded roller thrust bearing. The rollers and facing raceway of this bearing are protected from contamination by grit and dust by means of an O-ring snugly mounted in the groove provided by the chamfered shoulders 52 and 54 formed in the facing outer edges 40 and 42 of the bearing 38. The spring provides a dampening effect to the arm to reduce if not eliminate the vibrations which develop during the movement of the dressing device over the face of the grinding wheel. The O-ring when its stretched condition also acts as a partial dampener as well as providing a drag or brake to the rotative movement of arm 30 around the pivot pin 22.

Whether the member 10 is mounted on a base or a column of a machine tool it is desirable that the arm be rigidly attached to permit only a minimum vibration. Adjustment for the angle of dress of the face of the grinding wheel is provided by changing the angle of mounting of member 10. Whether by means of a wedge member 82 or by some other angle support, the arm in its retained condition is mounted so that the axis of the pivot pin is at right angles to the line of dress of the grinding wheel. The dressing device may be either a diamond, a carborundum (TM, The Carborundum Company, Niagara Falls, New York) stick or other dressing means carried in a holder which is adjustably carried in arm 30 so as to be precisely moved to the desired dressing condition.

It is to be noted that for the cup-shaped spring 70 a resilient member such as a rubber washer may be used. A flat metal washer under the head of the screw of course would be used to transmit the effective compressive force to the rubber washer. Instead of a roller bearing 64 other bearings such as porous bronze could be used. Instead of screw 74 in threaded aperture 66 the pivot pin 22 may have an exterior threaded end and a nut mounted thereon. The bearing 64 could be mounted in arm 10 and pivot pin 22 reversed in its mounted arrangement with washer 70 and screw 74 disposed on the bottom of the assembly of FIG. 1.

Terms such as left, right, up, down," bottom, top," front, back, in, out and the like are applicable to the embodiment shown and described in conjunction with the drawing. These terms as used are merely for the purpose of description and do not necessarily apply to the position in which the swing arm may be constructed or used.

While a particular embodiment of the swing arm has been shown and described it is to be understood the invention is not limited thereto and protection is sought to the broadest extent the prior art allows.

What is claimed is:

l. A swing arm assembly for holding a dressing device for grinding wheels and the like, said swing arm assembly including: (a) a fixed support member adapted for removable attachment to a base, column and like fixed portions of a machine tool carrying the grinding wheel to be dressed, said fixed member having one end formed to provide a determined flat surface and with a first aperture formed through this flat surface portion, this first aperture having its axis normal to the plane of the flat surface; (b) a swing member pivotally attached to and supported by one end of the fixed support member, said swing member having a flat surface portion formed at its pivoted end and with a second aperture formed through this flat surface, said second aperture having its axis normal to the plane of said flat surface; (c) a pivot pin providing the pivoted support of the swing arm on the fixed support member, said pivot pin mounted in and through said first and second apertures; (d) roller thrust bearing having opposed raceway members and mounted on the pivot pin and between the opposed flat faces of the fixed and swing members; (e) a resilient ring seal in a slightly stretched condition engaged in a groove formed by a chamfer on facing outer edges of the opposed raceway members of the thrust bearing, said seal preventing dust, dirt and the like from entering the bearing while also providing a brake action to the relative rotative movement of the thrust bearing raceways; (f) biasing means for urging the fixed and swing members toward each other while also providing a vibration dampner and pre-load to the thrust bearing, and (g) holding means provided on the distal end of the swinging arm for holding a dressing device for a grinding wheel, the holding means in combination with the dressing device adapted to be adjustably moved to a selected position in a plane parallel to the plane of the movement of the swing arm around the pivot pin.

2. A swing arm assembly for holding a dressing device as in claim 1 in which the pivot pin is a headed pin having thread means provided at least at the opposite shank end thereof and the biased means is a spring member which is adjustably compressed by a threaded member retained by the thread means of the pivot pin.

3. A swing arm assembly for holding a dressing device as in claim 2 in which the thread means of the pivot pin is a threaded aperture and the threaded member is a headed screw carried therein.

4. A swing arm assembly for holding a dressing device as in claim 3 in which there is provided a set screw also carried in the other end of the threaded aperture of the pivot pin, said set screw disposed to be tightened to retain the headed screw in its adjusted condition.

5. A swing arm assembly for holding a dressing device as in claim 2 in which the member against which the head of the pivot pin is drawn is provided with an anti-friction bearing disposed to engage the head of the pivot pin so that any relative motion of the member and the pivot pin is made with said anti-friction bearing interposed between the head and member.

6. A swing arm assembly for holding a dressing device as in claim 5 in which the anti-friction bearing engaging the pivot pin head is a ball bearing having both radial and thrust capacity.

Claims (6)

1. A swing arm assembly for holding a dressing device for grinding wheels and the like, said swing arm assembly including: (a) a fixed support member adapted for removable attachment to a base, column and like fixed portions of a machine tool carrying the grinding wheel to be dressed, said fixed member having one end formed to provide a determined flat surface and with a first aperture formed through this flat surface portion, this first aperture having its axis normal to the plane of the flat surface; (b) a swing member pivotally attached to and supported by one end of the fixed support member, said swing member having a flat surface portion formed at its pivoted end and with a second aperture formed through this flat surface, said second aperture having its axis normal to the plane of said flat surface; (c) a pivot pin providing the pivoted support of the swing arm on the fixed support member, said pivot pin mounted in and through said first and second apertures; (d) roller thrust bearing having opposed raceway members and mounted on the pivot pin and between the opposed flat faces of the fixed and swing members; (e) a resilient ring seal in a slightly stretched condition engaged in a groove formed by a chamfer on facing outer edges of the opposed raceway members of the thrust bearing, said seal preventing dust, dirt and the like from entering the bearing while also providing a brake action to the relative rotative movement of the thrust bearing raceways; (f) biasing means for urging the fixed and swing members toward each other while also providing a vibration dampner and pre-load to the thrust bearing, and (g) holding means provided on the distal end of the swinging arm for holding a dressing device for a grinding wheel, the holding means in combination with the dressing device adapted to be adjustably moved to a selected position in a plane parallel to the plane of the movement of the swing arm around the pivot pin.

2. A swing arm assembly for holding a dressing device as in claim 1 in which the pivot pin is a headed pin having thread means provided at least at the opposite shank end thereof and the biased means is a spring member which is adjustably compressed by a threaded member retained by the thread means of the pivot pin.

3. A swing arm assembly for holding a dressing device as in claim 2 in which the thread means of the pivot pin is a threaded aperture and the threaded member is a headed screw carried therein.

4. A swing arm assembly for holding a dressing device as in claim 3 in which there is provided a set screw also carried in the other end of the threaded aperture of the pivot pin, said set screw disposed to be tightened to retain the headed screw in its adjusted condition.

5. A swing arm assembly for holding a dressing device as in claim 2 in which the member against which the head of the pivot pin is drawn is provided with an anti-friction bearing disposed to engage the head of the pivot pin so that any relative motion of the member and the pivot pin is made with said anti-friction bearing interposed between the head and member.

6. A swing arm assembly for holding a dressing device as in claim 5 in which the anti-friction bearing engaging the pivot pin head is a ball bearing having both radial and thrust capacity.

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