Device for grinding compound-convex surfaces

Aug. 17, 1965 j. _A. lavallee 3,200,540

DEVICE FOR GRINDING COMPOUND-CONVEX SURFACES

Filed Nov. 5, 1963

Sheets-Sheet 1

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Aug. 17, 1965

J. A. LAVALLEE

3,200,540

DEVICE FOR GRINDING COMPOUND-CONVEX SURFACES

Filed Nov. 5, 1963

Sheets-Sheet 2

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BY

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Aug. 17, 1965 j. _A. lavallee 3,200,540

DEVICE FOR GRINDING COMPOUND-CONVEX SURFACES Filed Nov. 5, 1963 3 Sheets-Sheet 3

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3,200,540

Patented Aug. 17, 1965

United States Patent Office

3,200,540

DEVICE FOR GRINDING COMPOUND-CONVEX SURFACES

Joseph Aime Lavallee, Springfield, Mass., assignor to Lavallee &amp; Me, Inc., Chicopee, Mass., a corporation of New York

Filed Nov. 5,1963, Ser. No. 321,530

Claims. (CI. 51—73)

The present invention relates to the grinding of compound-convex curved surfaces, and more particularly to so grinding the end faces of reamer blades or other bladed cutting.

The object of the invention is to provide a simple and effective device for grinding compound-convex curved surfaces, particularly of spherical or ellipsoidal form.

A further object of the invention is to enable economical and accurate sharpening of reamers of the type disclosed in my prior Patent No. 2,940,342, as well as to similarly sharpening drills, taps and similar cutting tools.

The invention is characterized by the provision of an internal grinding surface on a rotating grinding wheel. This grinding surface is generated by a curved line swung about the axis of rotation of the grinding wheel. Means are provided for positioning a workpiece for engagement with this internal grinding surface to form compoundconvex curved surfaces thereon. In the case of sharpening reamers of the type referred to, the reamers are positioned for engagement of the end faces of successive blades with this internal surface which preferably has a simple concave configuration. Provision is made to accurately adjust the positioning means to obtain the necessary clearance or rake behind the cutting edges of the reamer blades which are thus sharpened. Further adjustments are provided so that in the grinding operation the finished surfaces may be accurately located, as desired.

In order to maintain the accuracy of the surfaces being ground, means are provided for dressing this internal grinding surface with a minimum of effort. These means are mounted in fixed relation to the workpiece positioning means and preferably take the form of a diamond point or the like which is rotated about an axis transverse to the axis of rotation of the grinding wheel to engage and dress the internal grinding surface of the wheel as it rotates.

While the invention may be embodied in a special purpose machine, it may advantageously be embodied in a fixture for use in combination with a surface grinder or the like. As such, it would comprise a workpiece or reamer holder which was adapted to be mounted on the bed of the surface grinder to position the reamer for engagement with an internal grinding surface of a wheel mounted on the usual spindle of such machines. Further, the fixture would preferably have means mounted thereon for dressing this internal grinding surface.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.

In the drawings:

FIG. 1 is a side elevation, partly in section and with other parts broken away, illustrating a device embodying the present invention;

FIG. 2 is a front elevation, with portions broken away, of this device;

FIG. 3 is a section, on an enlarged scale, taken on line III—ΙΠ in FIG. 1;

FIG. 4 is a section taken on line IV—IV in FIG. 2;

FIG. 5 is a perspective view of the end of a reamer blade ground by the device of the present invention;

FIG. 6 is a section, on an enlarged scale, taken generally on line VI—VI in FIG. 1;

FIG. 7 is a section taken on line VII—VII in FIG. 6;

FIG. 8 is a fragmentary view of a modified holder for larger reamers; and

FIG. 9 is a section taken generally on line IX—IX in FIG. 8.

As will be more fully apparent from this description, the present invention may be embodied in a special purpose machine or in a fixture to be used in combination with a surface grinding machine or the like, as herein shown. Surface grinding machines are well known and basically comprise (FIGS. 1 and 2) a bed 10 on which workpieces are mounted and a rotating spindle 12 on which various grinding wheels may be mounted by nut 11 threaded onto its outer end. In the present instance a cup-shaped grinding wheel 14 is shown mounted on the spindle 12. The bed 1® is adjustable horizontally in directions both longitudinally and transversely to the axis of the spindle 12. The bed is further adjustable vertically relative to the spindle. These adjustments of the bed 10 relative to the spindle 12 are provided by known means which are herein diagrammatically represented by lead screws 16,18 and 2®.

As herein disclosed, the invention takes the form of a fixture comprising a plate 22 secured to the bed 10 and having thereon a dovetail guide 24 extending transversely of the axis of the spindle 12. Normally the bed 10 is magnetizable to secure the plate 22 thereon, though other means could also be employed. A pedestal 26 is slidably mounted on this guide and positioned relative thereto by a lead screw 2S, threadably received by the pedestal 26 and rotatably received by a lug 30 attached to one end of the guide 24. A knob 32 is secured to the lead screw 28 to hold it axially fixed relative to the lug 30 and to facilitate rotation of the lead screw to position the pedestal 26 relative to the plate 22. A pointer 34 may be secured to the pedestal 26 and matched against indicia on a plate 36 secured to the guide 24 to provide a reference for adjustment of the pedestal. A set screw 38 may be threaded through the pedestal 26 and engage a gib 39 to lock the pedestal 26 relative to the guide 24 in adjusted position thereon.

The reamer holder 42 is pivotally mounted by means of a pin 44 and the illustrated clevis connection on a swivel block 46. Set screws 47 retain the pin 44 in place and also secure the holder 42 in adjusted angular position relative to the swivel 46. A pointer 48 and indicia marks 50 may be employed as a reference for this angular adjustment of the holder 42 about a horizontal axis transverse to the axis of the spindle 12.

The swivel 46 is pivotally mounted on the pedestal 26 for angular adjustment of the holder 42 about a vertical axis. Set screw 52 is provided to lock the swivel and with it the holder 42 in a given angular adjustment. Pointer 54 is secured to swivel 46 and may be set against indicia on plate 56 as a reference for such adjustment. The plate 56 is mounted at the upper end of the angularly fixed pedestal 26.

The holder 42 is also adjustable in a vertical direction heightwise of the plate 22 by reason of the pedestal 26 being extensible. The pedestal 26 comprises a lower member 58 which receives the longitudinal adjusting screw 28 and in which is formed the guideway for receiving the dovetail guide 24. The upper end of member 58 is threaded to receive a sleeve 60. The pedestal further comprises an upper member 62 which is also threaded to receive the sleeve 60. The threads on the members 58 and 62 are of opposite hand so that as the sleeve 60 is rotated, the height of the holder 42 may be readily and quickly adjusted. It will also be seen that pins 64 are :,200,540 ³provided to prevent relative rotation between the members 53 and 62. A set screw 66 may be employed to lock the sleeve 60 in any adjusted position. A lead plug 68 may be interposed between the set screw 66 in the threads of member 58 to prevent their being distorted.

The holder 42 further comprises a replaceable bushing 76 which is held in place by a set screw 72. The bushing 70 slidably receives a reamer R which, is angularly positioned relative thereto by a pin 74 at its forward end. The pin 74 (see also FIG. 3) enters a flute in the reamer between adjacent blades thereof to accurately position the leading face of the reamer blade relative to the grinding wheel 14.

More specifically, the holder 42 positions the reamer R for engagement with the end face of a reamer blade b with an internal grinding surface g (FIG. 6) formed on the cup-shaped wheel 14. The reamer R (FIG. 1) has a stop collar 76 removably secured thereto so that it may be positioned through the bushing 70 for engagement with the grinding surface g to a point limited by the collar 76. After the end face of a reamer blade has been ground, the reamer is retracted within the bushing 73. past the pin 74, and rotated to register another flute with the pin 74. The reamer is again advanced into engagement with the internal grinding surface g to a point limited by the collar 76. This process is continued until all of the reamer blades have been ground. The described means insures that the end surface of each blade will have the same configuration and each blade will have the same effective length.

The nature of the finished surface produced by the grinding surface g will best be understood with reference to FIGS. 5 through 7 illustrating the end face f of the reamer blade b and the cutting edge c, formed at the juncture of the end face f and the leading face I of the blade b. The grinding surface g may best be defined as being generated by a curved line swung about the axis of rotation of the grinding wheel 14. More specifically, the grinding surface g is a concave surface generated by a simple curved line and specifically an arcuate line extending from the outer surface of the grinding wheel 14 to the inner face thereof and swung about the axis of rotation of the grinding wheel. As illustrated in FIG. 2, the grinding wheel 14 is rotating in a counterclockwise direction. The leading face I of the blade b faces upwardly towards the direction of rotation of the wheel. The leading face I at its point of engagement with the surface g is preferably disposed in a horizontal plane extending radially of the axis of rotation of the wheel 14. This relationship is established by the pin 74 in the bushing 70. It is also preferable that the leading face I be angled somewhat greater than 90° from the surface g and this relationship may be established by the angle of the holder 42 relative to the pivot 46 as it is adjusted about the pivotal connection provided by the pin 44. The angle of tilt of the holder 42 about the horizontal axis of pin 44 controls the clearance or rake of the end face f behind the cutting edge c for the requirements of a given reamer.

With the established relationships a substantially sperical surface is ground on the end face f of the reamer blade b. As previously described, the end faces f of successive blades may be brought into engagement with the surface g to accurately grind this same configuration on each blade and thereby produce a blade not only having a curved cutting edge c, but one which has a maximum amount of reamer material behind the cutting edge for improved cutting action and wear characteristics, as more fully discussed in the above-mentioned patent.

The various adjustments provided for the holder 42 relative to the plate 22 as well as the adjustment of the bed 10 relative to the grinding wheel enable accurate control of the relative location of the spherical surface ground on the end face of each blade. Thus it will further be noted that it is advantageous to pivot the holder 42 about the vertical axis as provided by the swivel con nection between the swivel 46 and the pedestal 26. Also, the transverse location of the holder 42 will determine how closely the cutting edge c approaches a tangential relationship with the longitudinal edge of the blade.

The adjustments provided also permit displacement of the reamer so that it may engage the surface g at other points. If so displaced from the illustrated position, the configuration of the surface ground will tend to become of more pronounced ellipsoidal form.

In order to maintain the accuracy of the surface being ground, means are provided for periodically dressing or truing the grinding surface g.Such means are advantageously mounted on the plate 22 in predetermined relationship to the holder 42.

As illustrated, the dressing means comprise a diamond point 73 which may be swung about a transverse axis along the same line as generates the grinding surface g. The diamond point 78 is mounted in an arm 80 which extends laterally of the wheel 14 and is journaled in a block 82 for rotation about a horizontal axis preferably normal to the axis of rotation of the grinding wheel 14. It is also preferable that the axis of rotation of the arm 80 be disposed substantially in alignment with the front face of the wheel 14.

Swinging movement of the arm SO is illustrated in FIG. 1 which shows the limits of its movement in traversing the diamond point 73 across the grinding surface g. Preferably means are provided for preventing rotation of the arm 80 beyond these limits, such means taking the form of a pair of fingers 84 extending from a hub on the arm 80 and engageable with a pin 86 projecting from the block 82. A knob 88 is secured to the arm 80 to facilitate this rotation. It will be further noted that the arm 80 is relieved at 90 to provide clearance for the front face of the grinding wheel 14 within the limits of rotation thus established.

The diamond point 78 may also be employed to dress the front face of the wheel 14 as the surface g is worn away. This may readily be accomplished by traversing the bed: 10 in a vertical direction through the use of the vertical adjustment of the bed previously mentioned.

It will be seen that the diamond point 78 will have a desired heightwise and longitudinal relationship with the grinding wheel 14. The vertical and transverse adjustments of the holder 42 as provided by the extensible feature of the pedestal 26 and its movement on the guide 24 enable the holder to position the reamer R in the desired relation to the grinding wheel 14 in the . surface thereof. The grinding wheel 14 is illustrated as being of conical shape which means that as the surface g is worn away, the bed 10 will need to be progressively raised and further the holder 42 will need to be moved downwardly and inwardly to maintain the established relationship with the surface g. The cup-shaped wheel 14 may also take the form of a cylinder, rather than the illustrated conical form, in which case the need for adjustments between the diamond point 78 and the holder 42 will be minimized.

It will be apparent that different size bushings 70 would be employed for reamers of different diameters in order to maintain an accurate positioning of the reamers by the holder 42. Further, the present device may be used in sharpening spiral fluted reamers,: as well as straight fluted reamers, as illustrated. In this connection: it will be noted that the bushing 70 may be rotated within the holder 42 and then locked by set screw 72 to accurately position the leading face of the blade being sharpened relative to the grinding surface g, as above described.

The use of the bushing 70 to position the reamer R is preferable for smaller diameter reamers, but does have the limitation of requiring different size bushings for each different reamer diameter. FIGS. 8 and 9 illustrate a modification of the holder in which reamers R are mounted on “centers,” and a wide range of reamers may

8,200,540 , be ground without requiring change parts as the bushing 70.

In these figures a modified holder 42' is positioned by the pin 44 on the swivel block 46 as in the previous described embodiment, and all other elements of this embodiment may remain unchanged. The grinding wheel 14' is, however, modified to illustrate a cylindrical cupshaped wheel in place of the conical cup-shaped wheel. The grinding surface g formed thereon may be the same as before. A carrier 96 is slidably mounted in the holder 42' for movement generally axially of the spindle 12 towards and away from the grinding surface g. The carrier 96 is generally of a tubular shape and mounted at its forward end is a conical support or center rest 98 which is affixed to an arm 100 extending from an extension of the carrier 96 which is disposed interiorly of the cupshaped wheel 14'. The disposition of the carrier extension and the arm 100 is such as to avoid contact with the wheel 14'. This disposition is maintained by a key 102 secured to the carrier 96 and is guided by a longitudinal slot in the holder 42' so as to prevent rotation of the carrier 96 relative thereto.

A plug 104 is removably secured at the outer end of the carrier 96 to provide means for mounting a second conical support 106 formed at the end of a screw 108 threaded through the plug 104. The supports 98 and 186 engage centers in the opposite ends of the reamer R to position the reamer on the carrier. It will be seen that the reamer R may be removed from the carrier by removing the plug 104. Successive reamers may be introduced into the carrier 96 through the outer end of the reamer and then positioned on the supports 98 and ¹06. Variations in reamer length, within given limits, are accommodated by the extent to which the screw 108 is threaded through the plug 104.

A locating pin 110 projects from the end of an arm 112 secured to the holder 42' by a screw 114. Pin 110 enters the flutes of the reamer R to position its blades relative to grinding surface g, in the same fashion as pin 74, previously described. Provision is made by a slot 115 in the arm 112 for adjusting the relative position of the locating finger circumferentially of the holder 42' so as to obtain a proper angular disposition of the leading face of each reamer blade relative to the grinding surface g to obtain the same function as was previously had in rotating the bushing 70.

A collar 116 is adjustably secured to the carrier 96 and arranged to abut the holder 42' to limit the movement of the carrier towards the grinding surface g and functions in the same fashion as the collar 76 (see FIG. 1) to assure that the effective length of each of the reamer blades will be the same after grinding the end faces thereof.

It will also be noted that the carrier 96 is cut away at 118 to provide access to the outer end of the reamer R. This enables the reamer R to be rotated on the supports 98 and 106 as successive blades are brought into engagement with the grinding surface g. Thus, in operation, the carrier 96 is advanced toward the grinding wheel 14' until limited by the collar 116. The carrier is retracted to a point where the outer end of the reamer is clear of the locating finger 110. The reamer is then rotated on these supports to align another flute with the locating finger 110 and the carrier 96 again advanced. This cycle of operation is repeated until the end faces of all the reamer blades have been ground.

In the above description particular reference has been made to the grinding and sharpening of reamers, however, it will be apparent to those skilled in the art that the inventive concepts are also applicable to the grinding of other compound-convex surfaces as well as to sharpening like cutting tools having longitudinal blades and flutes, as for example, drills, taps and milling cutters.