US3467447A - Ball way package - Google Patents

Description

Sept. 16, 1969 w. G. NEWMAN BALL WAY PACKAGE 6 Sheets-Sheet 1 Filed June 22, 1967 u I X l p Q a J at Z 3 evade-row 2 nlldozm Gpnewman, Qdfl/ W, VJ; a

Sept. 16, 1969 w. G. NEWMAN BALL WAY PACKAGE 6 Sheets-Sheet 2 MVSMTOM Hiam CiQieaJ Sept. 16, 1969 w. G. NEWMAN 3,467,447

BALL WAY PACKAGE Filed June 22, 1967 6 Sheets-Sheet 3 C m TOYQJOBY/ Sept. 16, 1969 w. G. NEWMAN BALL WAY PACKAGE 6 Sheets-Sheet 4 MVSQTOK/ @Jdh'am G.7(ewnzan w wflw Filed June 22, 1967 WWW/A 2 Sept. 16, 1969 w. G. NEWMAN 3,467,447

BALL WAY PACKAGE Filed June 22, 1967 6 Sheets-Sheet 5 L/I/ AZ max/narrow j! TTOMS Y./

Sept. 16, 1969 w, G, M N 3,467,447

BALL WAY PACKAGE Filed June 22, 1967 6 Sheets-Sheet 6 52 zis United States Patent 3,467,447 BALL WAY PACKAGE William G. Newman, Oak Park, Mich., assignor to Beaver Precision Products, Inc., Clawson, Mich., a corporation of Delaware Continuation-impart of application Ser. No. 432,341,

Feb. 12, 1965. This application June 22, 1967, Ser.

Int. Cl. F16c 17/00, 21/00, 19/00 U.S. Cl. 308-6 4 Claims ABSTRACT OF THE DISCLOSURE A self-contained unit adapted to support member for movement on another, such as a way of a machine tool, and including one or more series of bearing balls. Each series of balls travels through the unit in a closed path which includes an active run where the balls project through the unit and roll between the surface of the way and an internal bearing surface in the unit.

Related application This application is a continuation-in-part of my copending application Ser. No. 432,341, filed Feb. 12, 1965, now abandoned.

Background of the invention This invention relates to a self-contained ball way package adapted to support one member for movement on and relative to another member, such as a way of a machine tool, and, more particularly, to a package which is formed with one or more closed paths in which bearing balls circulate. In each path, the balls travel along an active run where the balls project through the package and roll between an internal bearing surface in the package and one of the members such as the surface of a way.

Summary of the invention The invention aims to provide a new and improved ball way package which is comparatively simple and inexpensive to manufacture and which, at the same time, is compact in size. This is achieved by forming the body of the package in three parts which individually are relatively simple to make, which may easily be assembled together, and each of which forms a part of each ball path whereby the paths are completed by securing the three parts together. The invention also aims to reduce the possibility of failure by minimizing the lateral forces which the balls exert on the body of the package as they travel along the active run.

Brief description of the drawings FIGURE 1 is a perspective view, with parts broken away and shown in section, of a ball way package constructed in accordance with the present invention and mounted to support a carriage for sliding on a way.

FIG. 2 is a perspective view of the package from a different angle.

FIG. 3 is a sectional view taken along the line 33 in FIG. 2.

FIG. 4 is an enlarged fragmentary sectional view taken along the line 44 in FIG. 3.

FIG. 5 is an enlarged fragmentary sectional view taken along the line 5-5 in FIG. 4.

Patented Sept. 16 1969 FIG. 6 is a perspective view of the body portion of the package.

FIG. 7 is a perspective view of the part which forms the active run of the ball path.

FIG. 8 is a fragmentary sectional view taken along the line 88 i FIG. 4.

FIG. 9 is a fragmentary perspective view of the package and illustrates an alternate manner of mounting the package.

FIG. 10 is a perspective view of the third part of the package, this part forming the return run of the ball path.

FIG. 11 is an enlarged fragmentary view similar to FIG. 4.

FIG. 12 is a fragmentary sectional view taken along the line 1212 in FIG. 11.

FIG. 13 is a view similar to FIG. 12 but shows the results of lateral forces applied to the bearing balls.

FIG. 14 is a fragmentary sectional view, similar to FIG. 5, of a modified form of the invention.

FIG. 15 is a fragmentary sectional view taken along the line 15-15in FIG. 14.

FIG. 16 is a plan view of another modified form of the invention.

FIG. 17 is an enlarged fragmentary sectional view taken along the line 1717 in FIG. 16.

FIG. 18 is a fragmentary sectional view taken along the line 1818 in FIG. 17.

FIG. 19 is a fragmentary sectional view, similar to FIG. 5, showing still another modified form of the invention.

FIG. 20 is a fragmentary sectional view taken along the line 20-20 in FIG. 19.

FIG. 21 is a fragmentary sectional view taken along the line 21-21 in FIG. 19.

Description of preferred embodiments As shown in the drawings for purposes of illustration, the invention is embodied in a ball way package 10 for supporting a movable member 11 (FIG. 3), such as a carriage of a machine tool, for rectilinear movement on a way 12. The package 10 is adapted to be mounted on the carriage and is formed with one or more closed paths 13 through which a plurality of bearing balls 14 circulate. In this instance, there are four such paths, indicated by the reference characters 13, 13, 13" and 13" respectively (FIG. 4), and each path includes an active run 15, a parallel return run 16, and connecting runs 17 and 18 disposed at each end of the package and joining the active and return runs.

As the balls 14 travel along the active run 15 of each path, they ride on a bearing surface 19 which is formed interiorly of the package 10 and which parallels the surface 20 of the way 12. At the same time, the balls on this run project through the package to roll on the way surface 20. Thus, as the balls circulate along the paths 15, and support the carriage 11 for movement back and forth on the way 12 by rolling between the surfaces 19 and 20. As the balls move along the return path, they roll on another surface 19a which parallels the surface 19.

In accordance with the present invention, the ball way package 10 is constructed in a novel manner so as to be comparatively easy to manufacture and assemble and compact in construction while, at the same time, the package is capable of supporting relatively heavy loads for free travel along the way 12. To these ends, the package is formed from three parts 21, 22 and 23 which individually define parts of each path 13 and which fit together at easily machined surfaces so that, when assembled together they combine to define the entire path. Thus, the part 21 is a block which constitutes the body of the package and is sandwiched between the parts 22 and 23 which also are in the form of blocks or plates.

As shown in FIG. 3, the active run 15 of each path 13 is formed lengthwise along the block 22 while the return run 16 extends longitudinally along the block 23 and the connecting runs 17 and 18 extend through the block 21 adjacent the ends of the runs 15 and 16. The active and return runs 15 and '16 open inwardly through the plates 22 and 23 respectively so that the balls 14 in the path 13 roll on the faces of the body block 21 whereby these faces constitute the surfaces 19 and 19a. With this arrangement, the outer blocks 22 and 23 may be for-med as precision castings with the runs 15 and 16 cast as grooves in their respective blocks and the body 21 may simply be a block of bearing steel with holes drilled through it to constitute the connecting runs 17 and 18. The three blocks may then be secured together with the balls 14 in place in the paths '13 to complete the package 10.

In the present instance, the lower plate 22 or ball guide is cast with four grooves or channels which form the active runs 15 for the four paths 13, 13', 13 and 13" and the bottoms of these grooves terminate in slots 15a which open through the outer side of plate 22. As shown most clearly in FIG. 4, each groove 15 has parallel side walls 24 which are spaced apart a distance slightly greater than the diameter of the balls 14 to permit free traverse of the balls from one end of the groove to the other. The outer portion of each groove is formed by inclined walls 25 which merge with the side walls 24. The thickness of the plate 22 is somewhat less than the diameter of the balls so that, as the balls roll along the surface 19 of the body block 21, they project through the slots 15a and beyond the outer side of the lower plate 22 to ride on the way 12. At the same time, the walls 25 produce slots 1541 which are narrower than the balls and prevent the balls from dropping out of the grooves 15 when the package is separated from the carriage 11 and the way 12.

As shown most clearly in FIGS. 11, 12 and 13 the portions 22a of the plate 22 which forms the grooves are constructed and arranged to hold the later-a1 forces exerted on the bearing balls 14 down below a magnitude which is likely to cause failue of the package. To this end, the grooves are made as narrow as possible within the limits of manufacturing tolerances and, in actual practice, are only a few thousandths of an inch wider than the diameter of the bearing balls. Further, the strip portions 22a of the plate along the sides of the grooves are made to be comparatively rigid so as not to deform under those lateral forces which are produced. In this way the keystoning effect is reduced as is the possibility of failure due to keystoning.

The keystoning effect and how it can produce failure are demonstrated in FIGS. 12 and 13 in which the clearances have been exaggerated for purposes of illustration. As the balls 14 travel the active run 15, they become staggered due to the clearance between the balls and the walls of the grooves. Thus, one ball is against the right wall (FIG. 12) while the balls on either side of that one are against the left wall. Since the balls are under load, each ball exerts a force on the adjacent balls and the direction of each such force is along the line which connects the center of the balls. For example, the forces exerted on the center ball in FIG. 12 are indicated by the arrows a and b. Due to the staggering of the balls, these forces are at a small angle to the direction of travel of the balls and have lateral components which, when added together, produce a lateral force on the center ball as indicated by the arrow c. The ball, of course, transmits this lateral force to the strip portion 22a of the plate 22.

The magnitude of the lateral force is directly proportional to the clearance of the balls in the groove.

If the lateral force c is great enough to deflect the strip portion 22a, the keystoning effect becomes self-energizing. In other words, this deflection increases the offsetting of the balls and this increases the magnitude of the lateral force. This produces further deflection of the strip portion 22a which further increases the magnitude of the lateral force This action continues until the strip portion fails. The increase in the lateral force upon deflection of the strip portion is illustrated by the force arrows a, b and c in FIG. 13. In the present construction the possibility of such a failure during normal service is kept to a minimum by keeping the clearances and hence the magnitude of the lateral force as small as possible and by making the strip portions 22a rigid enough to resist initial deflection under this force. The self-energizing action, therefore, does not begin in the first instance.

While the upper plate 23 or ball return may be formed with closed grooves or channels to define the return paths 16; it is preferred to make the ball return in such a manner that the castings for the ball guide 22 and the ball return 23 are the same. For this purpose, the ball return is cast with grooves 16, which, like the grooves 15, are defined by parallel side walls 26 and inclined walls 27, the ball return when assembled being inverted relative to the ball guide. The only difference between the ball return and the ball guide is that the side walls 26 are wider than the side walls 24 so that the balls 14 when traveling along the return runs do not project up through the open slots 16a (see FIG. 4).

With the foregoing arrangement, the ball guide 22 and the ball return 23 may be made as identical castings which are like the ball return except there is a small amount of extra metal along the top and bottom surfaces. These surfaces are ground to reduce the part to the proper thickness for the ball return while leaving a surface 28 which mates with the body 21 as well as a ground outer surface 29. For the ball guide, the outer side of the casting is ground the same as for the ball return to leave an outer surface 30 similar to the surfaces 29. In grinding the inner side to form the surface 31, however, more metal is removed whereby the side walls 24 are shortened to the point where the balls 14, when contained within the slots 15, project beyond the surface 30.

The body block 21 may simply be a piece of bearing steel cut or otherwise shaped to the proper size with the faces 19 and 19a ground to mate with the opposing surfaces 31 and 28 of the blocks 22 and 23. Since the load of the carriage 11 is transmitted to the way 12 through the balls 14 in the active runs 15 and the face 19 of the body block, it is necessary to harden only this face. Preferably, however, both faces 19 and 19a of the block 21 are hardened so that each face may be mated interchangeably with the ball guide 22 and the ball return 23. At one end of the body block 21, four holes are drilled to form one set of connecting runs 17 while a similar set of holes are drilled at the other end to constitute the runs 18. The holes 17 and 18 connect opposite ends of the grooves 15 in ball guide to the corresponding ends of the grooves 16 in the ball return. Preferably, the ends of the grooves 15 and 16 are defined by inclined walls 32, which herein are rounded (FIGS. 5, 7 and 10) to facilitate the movement of the balls 14 into and out of the active and return runs.

In the present instance, the ball guide 22, the body 21 and the ball return 23 are secured together by rivets 33 which project through alined holes 34, 35 and 36 drilled in these parts adjacent both ends. Preferably, the rivets are hollow and the ends of the rivets are upset in counterbores 37 and 38 (FIG. 8) at the outer sides of the ball guide and ball return so that the rivets are disposed completely beneath the surfaces 29 and 30.

Advantage may be taken of the hollow rivets 33 to mount the ball way package 10 directly on the carriage 11 or to an interposed mounting plate 39 as shown in (FIG. 3) the plate is secured to the underside of the carriage by screws 40 projecting through holes 41 in the plate and threaded into the carriage. Pins 42 are secured to the mounting plate, one at each end thereof, and project down to be received in the hollow rivets 33 as shown in FIG. 8. The pins 42 are the type known as roll pins, that is, they are hollow and split longitudinally at 43 and are made of spring steel. The normal diameter of the pins is slightly greater than the internal diameter of the rivets so that the pins contract, as permitted by the slot 43 3, they are inserted in the rivets. Due to their resilience, the pins expand against the insides of the rivets and hold the package firmly with the surface 29 of the ball guide against the exposed surface 44 of the mounting plate.

In some instances, it may be desirable to mount the ball way package without using the plate and, to this end, provision is made to support the package by clips 45 (FIG. 9) which hold the ball return 23 directly against the carriage. Each clip includes a bar portion 46 which can be fastened to the carriage by screws (not shown) which project through holes 47 in this portion. The clips are mounted on the carriage so as to be just beyond the ends of the package and include fingers 48 which are formed at each end of the clip and which project downwardly from the bar portion and then toward the package to be received in recesses 49 in the latter. The recesses may be cast in the corners of the ball return 23 in which case similar recesses will be formed in the ball guide since the ball guide and ball return are ground from identical castings. The fingers thereby support the entire package through the ball return.

Due to slight manufacturing inaccuracies, the plates 22 and 23 and the block 21 may not be perfectly alined in which case the balls 14 may have some difficulty in entering and leaving the holes or connecting runs 17 and 18 in the block. This is overcome in the modification illustrated in FIGS. 14 and in which similar parts are indicated by the same but primed reference characters. Thus, the entrances and exits of the holes are cut away at about a 45 degree angle as indicated at 50 and 51. The cuts are arcuate in cross section with the diameter of the cuts being the same as the diameter of the holes. Thus, the cuts have a tear drop shape as illustrated in FIG. 15.

As a bearing ball 14 enters the active run 15, it is guided by the lower cut 51. It is important, therefore, that the axis d of this cut (FIG. 15) be in the same vertical plane as the center line of the groove. In this way, the cut guides the ball into a centered position within the groove. Were the axis of the cut at an angle, the cut would force the ball to one side and this would impose an added lateral force component on the preceding ball and increase the keystoning effect described above.

A ball way package constructed in accordance with the invention may also be arranged to support a rotating member. Such an arrangement is illustrated in FIGS. 16, 17 and 18 in which similar parts are indicated by the same but double-primed reference characters. As in the other embodiments, the package is made of a guide plate 22", a bearing block 21" and a return plate 23". In this instance, however, the grooves 52, 53 and 54 are curved and are arcs of concentric circles which have their centers at e (FIG. 16). Thus, the radii of the three grooves are the distances indicated at R1, R2 and R3 respectively. Ideally, the center e should also be the center of rotation of the member supported by the package but, in practice, the two centers may be offset by as much as an inch or two. Preferably, the grooves 55 in the return plate 23" are also arcuate although these grooves may be straight.

The form shown in FIGS. 16, 17 and 18 also has the bearing block cut away at 50" and 51". In this instance, however, the axis of each cut is in a plane which is tangential to the arcuate center 1 of the associated groove at a point g at the end of the cut.

- To insure further that the bearing balls, when under load, travel a straight line and do not deflect laterally, the paths of the balls may additionally be defined by grooves in the bearing block. Such an arrangement is shown in the modification illustrated in FIGS. 19, 20 and 21 in which similar parts are indicated by the same but triple primed reference characters. For this purpose, the underside of the block 21" is formed with longitudinal grooves 52 which are precisely centered with the paths 15" and merge at each end with the tear drop cuts 51'. Preferably, the grooves are arcuate in cross section and the radius of curvature is approximately the same as the radius of each ball 14". Thus, the load bearing capability of the assembly is increased since the balls engage the bearing block 21" with line contact instead of point contact. Similar grooves 52a may be formed in the top side of the block so that the latter may be assembled with either side down.

It will be observed that a ball way package 10 constructed in accordance with the present invention is compact and rugged and, yet, is comparatively simple to manufacture and assemble. Thus, the ball guide 22 and the ball return 23 may be made as precision castings and, in fact, as identical castings if desired, and need only be ground and drilled. The body 21 may simply be a block of bearing steel which also is ground and drilled and the three parts are assembled easily by the rivets 33. At the same time, the package is capable of supporting loads of substantial magnitude.

I claim as my invention:

1. A ball way package comprising, in combination, an integral block having a top surface and a flat bottom surface, a plurality of first holes extending through said block from said top surface to said bottom surface and disposed adjacent but short of the ends thereof, said first holes being parallel to each other, a plurality of second and similar holes extending through said block adjacent the other end thereof, the number and spacing of said second holes being as that of said first holes whereby said first and second holes are arranged in pairs, a plurality of endless series of balls, there being one series for each of said pair of holes, the balls of each of said series being uniform and smaller in diameter than said holes and arranged side to side in the form of an elongated endless loop having end rows disposed in the corresponding ones of said holes and intervening upper and lower rows extending along said top and bottom surfaces for rolling contact therewith, a separate bottom plate clamped against said bottom surface and providing a plurality of upwardly opening channels shallower than said ball diameter, there being a channel for each of said series of balls and each channel confining the balls of said lower row and guiding the latter into and out of the lower ends of the corresponding ones of said holes, each of said channels having a bottom slot narrower than said ball diameter with the lower portions of the balls projecting therethrough for rolling contact with a supporting surface, a top plate clamped against said top surface and providing channel shaped raceways for the balls of said upper rows and guiding the latter into and out of the upper ends of said holes, the width of the channels in said bottom plate being only slightly greater than the diameter of said balls, and a plurality of grooves, one for each of said holes in said block and each extending downwardly and inwardly from the lower portion of the corresponding hole to the associated channel, each of said grooves tapering toward the center of the width of the associated channels whereby said grooves center said balls in said channels and the balls enter the channels and are guided into a centered position within each channel to decrease the lateral forces acting on the balls.

2. A ball way package as defined in claim 1 in which a third groove is formed in the bottom surface of said block and extends from said first groove to said second groove, the centerline of said third groove paralleling the References Cited centerline of the channel in said bottom plate to main- UNITED STATES PATENTS tam said balls centered in the channel.

3. A ball way package as defined in claim 2 in which 719,951 2/1903 Norwood said third groove is arcuate in cross section and the radius 5 FOREIGN PATENTS of curvature of said third groove is substantially the same 499,758 11/1919 France.

as the radius of each of said balls. 569,650 1/1924 France- 4. A ball way package as defined in claim 1 wherein the channels in said bottom plate are arcuate with the MARTIN P SCHWADRON Primal. Examiner radius of curvature of the arcuate channels lying in a y plane passing through the lower surface thereof. 10 FRANK SUSKO, Assistant EXaIIlinfiT

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