US2206769A - Machine for finishing surfaces - Google Patents

Description

July 2, 1940. R. s. DRuMMdND 2,206,759

MACHINE FOR FINISHING SURFACES I Original Filed Feb. 8, 1937 3 Sheets-Sheet l FlGoi.

' ROBERT smummono BY MM ATTORNEYS.

July 2, 1940. R 5. DRUMMOND. 2,206,769 MACHINE FOR FINISHING SURFACES Original Filed Feb. 8, 1937 5 Sheets-Sheet 2 if: ROBERTS!) BY WW,W

INVENTOR.

. RUMMZNZ ATTORNEYS.

July 2, 1940. S R. s. DRUMMOND 2,206,769

MACHINE FOR FINISHING SURFACES Origigal Filed Feb. 8, 1937 3 Sheets-Sheet 5 FIG. 20.

INVENTOR.

ROBERT $.DRUMMQND BYW a ATTORNEYS.

Patented 1.1, 2, 1940 'umrro srATEs MACHINE FOB FINISHING SURFACES Robert S. Drummond, Detroit, Mich, might)! to National Breach & Machine Company, Detroit, Mich, a corporation of Michigan Original application February 8, 1937, Serial No.

Divided and this application October 11, 1937, Serial No. 168,509

16 Claims. (CL 90- 15) The invention relates to apparatus for finishing round or fiat surfaces, and more particularly it relates to a new art of removing metal from such surfaces which, in its accuracy of finishing,

resembles more nearly the art of grinding, but

which nevertheless is distinctly a cutting or shaving operation resulting in the removal of fine chips or shavings from the surfaces. This ap-- plication is a division of my pending application for patent Serial No. 124,790, filed February 8,

The invention in its broader aspects has many and varied uses, and this application is directed to the invention in its broadest sense. On the other hand, the application is also directed to certain specific embodiments of the invention and therefore in the description hereinafter given, reference will be made particularly to a method and apparatus for finishing flat and Q cylindrical surfaces such as will be found, for

example, on axle shafts for motor vehicles.

An object of the invention is to provide a rotary cutting tool capable of removing extremely fine shavings from metal surfaces and which is oper-- as able at pressure greatly less than that for cutters now employed for finishing surfaces.

A further object is to provide a machine adapted for rapid and accurate finishing of round and flat surfaces.

80 A more specific object of the invention is to develop a machine and suitable cutting tools therefor which are adapted for the simultaneous finishing of adjacent round andilat surfaces.

These and other objects are accomplished by so the apparatus hereinafter more fully described and illustrated in the accompanying drawings,

wherein Fig. 1 is a plan view of a machine embodylns my invention; 40 Fig. 2 is a partial end view of the machine;

Fig. 3 is a partial end view of a carriage and guideways therefor;

Fig. 4 is a section taken on line H of Fig. 1: Fig. 5 isan enlarged fragmentary perspective 45 of one of the cutters;

Fig. 6 is a fragmentary section of several adjacent cutting teeth;

Fig. 7 is a diagram illustrating a modified method of shaving round and flat surfaces; to Fig. 8 is a, diagram showing one method of arranging the cutter with respect to a; cylindrical.

surface;

Fig. 9 is a diagram at right angles thereto; Fig. 10 is a view similar to Fig. 8 showing a 6d modified arrangement:

- methods;

Fig. 11 is a view at right angles to Fig. 10;

Fig. 12 shows a modified cutter;

Fig. 13 is a diagram showing a method of feed-' ing a cutter to finish round surfaces;

Figs.l14 and 15 are diagrams at right angles '5 to one anotherillustrating another method of feeding for finishing round surfaces;

Fig. 16 is a diagram illustrating a modified cutter for finishing a corner radius in addition to a round surface; 10

Fig. 1'? is a diagram illustrating modified methods of feeding to finish a surface to the required size;

Fig. 18 is a similar diagram showing other Fig. 19 is a diagram similar to Fig. 10 showing a modified form of cutter; r

Fig. 20 is a diagram showing'the method of obtaining a uniform cylindrical surface when the axes of the tool and the cutter are crossed. go

In the drawings, the base of the machine is indicated at Ill. Adjustably mounted on the base on suitable guideways shown at II in Figs.

2 and 3, are a tail stock I2 and tool carriages l3 and It. Each carriage is adjustable on a guide ii, the initial adjustment being made by means of setting wheels it, ll. The tail stock is set by manipulation of handle it, the work being held by the tail stock and a center it on the base. As shown in Fig. 1, the particular type of work to be finished is an axle 20 having a cylindrical bearing surface it and a bevel gear 22 formed integral with the axis, theback face 2! of the gear and the surface II being those surfaces which are to be finished.

Each of the carriages l3, l4, and its guideway is angularly disposed to the axis of the axle to be finished. On each carriage there isjournaled a cutting tool indicated at 24, II. The axis of each cutteris disposed at a right angle to its particular guideway. and the cutter has a cutting face angularly disposed to the axis of the tool.

In Fig. 1 it will be seen that the tool resembles a bevel gear having spiral teeth thereon. The angle of the cutting face issuch that when the tool is moved into cutting relation with the work, it will be parallel to the surface to be fin- In the drawings are shown four motors, all indicated by the numeral 2', one for each of the tools, another for rotating the work, and still another for operating means to reciprocate the tools inward and from the work. Connecting the motors and their respective driven members are belts or chains 21 and suitable speed reduction mechanism 28. Initially, the tools are set on guides I5 to make a definite plunge cut in the surfaces to be finished. The means for subsequently moving the tools towards and from the work include a cam 29 fix'ed with relationto worm wheel 30, the latter beingrotated by worm 3i forming part of the reduction mechanism between the cam and its driving motor. Each'of the guides i5 is connected to one link 32 of a toggle mechanism 33, the other link 3% of which is pivoted to link 32 at 35. The pivot 35 is movable in an arcuate path about shaft 36, having means thereon for rocking the toggle. The axis of shaft 36 is fixed with relation to the base of the machine. It will thus be seen that the connection between link'32 and guide it is movable towards or from shaft 3% as the toggle is straightened or bent.

Ihe means for rocking shafts fiflt include an arm 3? keyed to each shaft and a connecting link til, the ends of which are -piv0tally connected to arms 37. Mounted on link dais a roller 39 adapted to cooperate with an elongated opening at in one end of lever an, the latter being pivoted intermediate its ends'to the base at 32. At the other end of the lever is a cam follower d3 cooperating with cam 29. It will be seen that cam 29 is provided on its peripheral-face with a low portion dd permitting follower t3 to move radially toward the center of the cam whereupon roller 39, link 38 and arms 37 are moved. This results in a bending of the toggles, which in turn simultaneously move the carriages and the tools carried thereby away from the work. This movement may be effected by suitable spring mechanism or a track cam if desired. Also, suitable automatic limit switches for stopping the motor while the machine is being loaded and unloaded are provided.

The arrangement of the carriages and crossed axes just described obviously permits the advance of tools of relatively small diameter towards and into cutting relation with the work, although their driving mechanisms may be somewhat larger than the tool itself. Also, the pressure angle of the cutting face permits shaving of the surface with less compressionof the metal. Because the driving means for the tool and work are independent of each other, it is possible to regulate the cutting actions of the tools and thus insure the most efficient operating conditions for finishing two surfaces, like or unlike, simultaneously.

In Figure 1, it will be noted that the cutting tool 24 is used for finishing the round surface 2! and the cutting tool 25 is used for finishing the fiat surface 23. Figure-5 shows an enlarged perspective view of the cutter 26. While my invention in its broader aspects contemplates cutters of various types, I will first specifically describe one form of cutter which has proven very satisfactory for commercial production in the finishing of axle shafts. The cutter M has spiral teeth 50 formed in the beveled face of the tool and, as shown, the teeth are disposed in the form of a left-hand-spiral. In the particular cutter illustrated, the distance between adjacent teeth in normal section is .160 of an inch. The tops 5| of the teeth have a width of of an inch and are backed off or relieved at a suitable angle a, such as 2. Intermediate adjacent teeth are recesses 53 of a suitable width and depth to carry away the shavings, and, as shown, this depth is of an inch. The recesses are so shaped as to provide a suitable rake on the front R. P. M., and the cutter 25 at 250 R. P. M.

face 54, such as a rake angle p of 5. The cutter as shown has an outside diameter of 6% inches and a face width. of 1 inch. The tool 24 is designed to operate in the shaving of the round surface 2l, the diameter of which is 1 inches.

The other cutter 25 is constructed to shave the fiat surface surface 23, which is an annular surface extending radially outward from the round surface 2!. The face extends to the outer diameter of the gear 22 which is 2% inches in diameter. The cutting tool 25 is constructed in the same manner as the cutting tool it, but the teeth are in the form of a right-hand spiral instead of a left-hand spiral. I

It is important that the relative rotations of the cutting tools and the axle be properly determined, and one relationship which has proven satisfactory in this specific case is to rotate the axle 2d at 425 R. P. M., the cutter 2d at The direction of rotation is also important, since it is desired that-the movement of the work surface past the cutting tool should be against the spiral angle of the tool. The directions of rotation are indicated in Figure l, the arrow 55 indicating the direction of rotation of the axle 2d, and the arrows 56 and 5? illustrating respectively the rotation'of the cutters 2d and 25.

With the cutting tools and speeds as above described, it has been found that both the round and fiat surfaces to be finished can be finished very accurately by the plunge cutting previously described. The direction of feed of the cutters 2d and 25 during the plunge cut is inward along the axes of carriages i3 and M respectively, at

.a small angle to the surface of the work. For

the finishing of these surfaces to a desired stand, it ordinarily requires the removal of .012 of an inch on each side of the round diameter 2i, and the removal of .020 of. an inch from the fiat surface 23.

It is to be understood that the specific data with respect to the cutting tools, rotations, feeds, etc., have been given above merely by way of example and is capable of considerable modification. However, to obtain good shaving action. it is necessary that the various factors, described above, be definitely correlated, and the example has been cited to show one suitable way for obtaining these results.

In the machine as illustrated in Figure l, the

' shaving action is efiected by plunge cutting only,

but the invention is also capable of embodiment in other modified methods. For example, it may be desirable to introduce a slight oscillation or single cross feed at the end of the plunge cutting cycle in a direction parallel to the surface to be finished. Such an additional movement has the tendency to improve the surface finish by "cleaning up the slight imperfections or tool marks which may be left by the plunge cut operation. This is diagrammatically illustrated in Figure 7. The cutter 25 is given an oscillation indicated by the arrow 60 parallel to the surface 23, and the cutter 24 is given an oscillation indicated by the arrow 6| parallel to the axis of the shaft This oscillation is preferably imparted only at the conclusion of the plunge cutting stroke and is ordinarily of relatively small amplitude, since this is sufficient for cleaning up the surface.

lid

Sit

shown in Figure 1, the axes of the cutter 24 and the axle lie in the same plane. The relationship of the parts is shown in the diagrams, Figures 8 and 9, where 82 is the axis of the cutter 24 and 63 is the axis of the round work piece It. In Figure 9 both axes appear to be coincident.

The invention also contemplates the finishing of round surfaces where the axes of the work and cutter do not lie in the same plane but are crossed at a limited angle. This is diagrammatically illustrated in Figures 10 and 11 where 85 represents the axis of the cylindrical work piece 66, and 81 is the axis of the cutter 88. when the axes are crossed as illustrated, the zone of contact instead of extending across the face width of the cutter as inFigure 8, would extend only for a limited distance on each side of the center 69 of crossed axes. In other words, at the points 10 and ii there would normally be a certain amount of clearance or backlash due to the crossed axes relationship. In order to compensate for this backlash, the double cutter 68 has its surface hollowed or dished as indicated by the line 12, and by properly proportioning the explained in Figure 20. I

amount hollowed out, the cutter can be provided with a surface which will cut uniformly over the entire face width of the cutter.

that where a cutter is not dished but has a straight bevel surface, the finishing actionalong the surface of the cylindrical work 66 may be obtained by a feed movement in the direction of the axis of the work, or other direction as A modified form of rotary cutting tool is shown in Fig. 12. This cutter I3 is generally similar to the cutter 24 shown in Fig. 5, except that the teeth 15 are inclined at a greater helical angle and now resemble worm threads. In the construction illustrated, there are eight threads, each having a lead equal to the width of the cutter, which .is in this case approximately 1 inch. As shown, the width of the lands It is approximately equal to the width of the gashes I1, and the depth of each gash is equal to its width. These dimensions of course may be varied under different working conditions. It'has been found that excellent results may be obtained working with tools having the widths of their teeth and recesses and the approximate depth of the recesses all .060 of an inch. In some instances it may be desirable to provide shallow concave grooves 18 in the faces of the lands, thereby to reduce the contact surface of the tool on the work. Regardless of whether the lands are straight or vgrooved, it is apparent that a plurality of closely spaced cutting edges operate simultaneously on the work. Since these lands are disposed angularly to the line of contact between the work and the tool, the point at which the cutting edge engages the work constantly shifts upon rotation of the tool or the work, or a combined rotation of the work and the tool.,

The rotation of the tools and the work is so timed that the cutting speed can be regulated to obtain the best cutting results.

Obviously the faces of the lands act as limiting gauges and, depending on the pressure on which the tool is forced against the work, the depth of the out can be controlled to shave the work to a minimum hitherto impossible with the known types of cutting tools. Since the ordinary pressures necessary to cut with the present method are much reduced, the heating'of the work due to the cutting action is reduced to a minimum. It has been found in practice that the shavings and chipsare not discolored as is the case when cuts of several thousandths of an inch are taken, most tools having to dig into the metal to such an extent that the metal removed shows un- -work during the cutting operation, it is obvious that means for moving either the work or the tools, or both, to effect relative axial movement thereof, may be employed. Under some circumstances it may be'found desirable to gear the work and tools, in which case a single drive motor is contemplated, but for flexibility and variety of operations, it has been found expedient to employ independent drives.

Referring again to Figure 1 which shows rotary cutters operating on both round and flat surfaces, it is desired to point out that by reason of the arrangement of the cutting edges on the tools, together with the fact that both the tools and the work are simultaneously rotated, an entirely novel type of cutting action takes place. The chips made by these tools are slivers, and unlike chips from milling cutters or other machine tools which are normally used for finishing surfaces. The chips from the cutting tools 01 my invention have more the appearance of lathe chips and are not upset as much as the chips from milling cutters. This may be explained from the fact that the teeth on the cutter cut more nearly around the work piece in a generally circular direction and do not cut straight across thepiece, even though the cutting edges of the teeth contact at points lying in a straight line. Generally speaking, the cutting edges cut the work piece along lines which are transverse to the axis of the work, and extend at an angle between 10 and Thus the cutting edges take long chips from the surface by cutting in a thread-like path, but finish a uniform surface shape whether this 1 be a flat surface or a round surface.

In Figure 13 I have shown a modified method of finishing a round surface to the specified dimensions. In this figure, 80 represents the cylindrical work piece and N the cutter. Instead of plunge feeding as shown in Figure 1, I provide a cross feed of the cutter relative to the work in the direction of the arrow 82. Thus the cutter is first offset laterally with respect to the work and is fed toward the work for a distance 83 sufficient to give the specified depth of cut; and the cutter is then fed in the direction of the arrow 82. This finishes the cylindrical surface completely to a predetermined size. If it is desired to reduce the size still further, the cutter may be again fed toward the work and again caused to traverse in the direction of the arrow 82, or in the opposite direction.

Figures 14 and 15 further illustrate methods of finishing round surfaces in accordance with my invention, In this case, the cylindrical work piece 84 is acted upon by the beveled rotary cutter cross-feed in the direction of the arrow I00.

35, and the arrows tit and 87] indicate alternative 87: shows the feed in a plane transverse to the axis of the rotary cutter i235. Either of these infeeding motions may be combined with a crossfeed as indicated by the arrow 88B. Again the cross-feed may be in the reverse direction as indicated by the arrow as.

in Figure 16 I have indicated a method for fin ishing cylindrical surfaces having a corner radius, or fillet, to adjacent the cylindrical surface at. In this case, the beveled cutter 92 has the beveled surface t3 rounded as at 94% to correspond in shape to the corner radius iii. The teeth 95 in-this cutter are formed, as in the previously described cutters, by a series of grooves or extending helically. These grooves. must be of sumcient depth at the rounded corner he so that the tops of the lands intermed ate the grooves when rounded will still leave sumcient depth of groove to form the cutting edges.

Figure 17 illustrates a further method of finishing cylindrical surfaces slightly modified from that illustrated in Figure 1. The cylindrical surface 26 is acted upon by the" beveled face of the cutter 2d. The surface may be completely finished by means of a plunge out toward the work in the direction indicated by the arrow 91 which is in a plane perpendicular to the axis cylindrical to the work. However, the direction of ,feed of the plunge cut may be along some inclined line as indicated by the arrow 08, in which case it is only necessary that the beveled surface 99 of the cutter be of sufficient width to contact with the entire active surface of the work 2|, both at' the beginning and the end of the plunge but.

dicated in Figure 18 were, instead of having merelyja plunge cut as indicated by the arrows 91 and 98, there may also be combined a. single that the grooves forming the cutting edges extend in a helical path. However, in some instances, it

may be desirable to have these grooves radialas indicated in, Figure 19. In this figure the cylindrical work piece I02 is acted upon by the cutter I03-in which the grooves I04 extend radially.

To further illustrate the method of finishing a. cylindrical surface, reference should be made to Figure 20. In this case, a relatively wide cutter I05 is used for finishing the cylindrical bearing surface I06. The axis I01 of the cutter is crossed with respect to the axis I08 of the work piece. Instead of moving the cutter in the direction of its axis to spread the finishing action over the surface of the work, it may be moved in some other direction as indicated'by the arrow I09. Thus it will appear that the axis I01 of the cutter will move from the position I09a to the position I001). The points where the two axes cross, thus progressively spread across the face of the cylindrical work pieceaswill be evident by the letters a, b, c, d and e. This action can either be the translation of a straightfaced cutter as illustrated in Figure 20, or a dish-' type cu tter as illustrated in Figures 10 andil.

In either case, the 1.-=- action is transferred the cutting action uniformly.

What I claim as my invention is:

i. A machine for finishing a work piece having a surface of revolution comprising a frame, heads on said frame for mounting said work piece, a motor for rotating said work piece, ways on said frame, a tool carriage on said frame guided by said ways toward and away from said work piece, a motor on said carriage, means for supporting ,a tool on said carriage, connections between said tool andsaid last mentioned motor for driving said tool from said motor independently of said work piece, a third motor on said frame, and means driven by said third motor for feeding said carriage a predetermined distance toward said work piece and return.

2. A machine for finishing a work piece having a surface of revolution comprising a frame, heads on said frame for mounting said work piece, a motor for rotating said work piece, ways on said frame, a tool carriage on said frame guided by said ways toward and away from said work piece, a motor on said carriage, means for supporting a tool on said carriage, connections between said tool and said last mentioned motor for driving said tool from said motor independently of said work piece, a third motor on said frame, means driven by said third motor for feeding said carriage a. predetermined distance toward said work piece and return, and means for stopping said motors upon completion of said return stroke.

3. A machine for finishing a work piece having a surface of revolution comprising means for rotating said work piece, means for mounting a rotary tool having a working surface adapted to engage said surface of revolution in line contact, means for rotating said tool independently of said work piece, and means for feeding said tool toward said work piece along a path having a component perpendicular to said fine of contact and a component parallel to said 4. A machine for finishing a work piece having a surface of revolution comprising a, frame, means on said frame for mounting said work piece, means for rotating said work piece, ways on said frame, a tool carriage on said frame guided in said ways, means on said carriage for supporting a rotary tool with its working surface positioned to engage said surface of revolution in line contact, means for rotating said tool, and means for feeding said carriage a predetermined disiance toward said work piece, said ways forming an oblique angle with said line of contact.

5. A machine for finishing a. work piece having a surface of revolution comprising a frame, a work support on said frame, a motoron said frame for rotating said work support, a tool carriage mounted on said frame for movement toward and from said work support, a tool support on said carriage, means for rotating said toolsupport, and feeding means for said carriage comprising means for moving said carriage toward said work support at feeding speeds, said last means responsive to feeding motion to reduce the rate of feeding movement near depth to finish said work piece. with fine cuts.

6. A machine for finishing a work piece having a surface of revolution comprising a frame, a work support on said frame, a motor on said frame for rotating said work support, a tool car- 1.

aaoaree riage mounted on said frame for movementtoward and from said work support, a tool sup- P rt on said carriage, means for rotating said tool support, and feeding means for said carriage comprising cam-controlled toggle means for moving said carriage toward said work support at'feed lng speeds and reducing the rate of feeding movement near depth to finish said work piece with fine cuts.

7. A milling machine comprising a work support, a pair of tool carriages independently mounted for traverse toward and from said work support; toggles for each tool carriage, each comprising a link pivoted to a carriage, and a second link pivoted at one end to said first link and mounted for rotation about a fixed point on said machine, and means for simultaneously swinging said second link about their fixed pivots to traverse said carriages.

do A milling machine comprising a work support, a pair of tool carriages independently mounted for traverse toward and from said work support; toggles for each tool carriage, each comprising a link pivoted to a carriage, and a second link pivoted at one end to said first link and mounted for rotation about a fixed point on said machine, and means for simultaneously swinging said second link about their fixed pivots to traverse said carriages, said last named means comprising a cam, a lever movable by said cam, and a link movable by said lever and connected to both of saidsecond mentioned links.

9. A milling machine comprising a work support, a tool carriage movable obliquely toward and from said work support, a tool support on said. carriage, a toggle comprising a pair of links movable to aligned position to feed said carriage to-depth, to decrease the rate of feed near. depth.

10. A milling machine comprising a work support, a tool carriage movable obliquely toward and from said work support, a tool support adjustably mounted on said carriage, a toggle com prising a pair of links movable to aligned position to feed said carriage to depth, to decrease the rate of feed near depth.

ii. In a machine for finishing surfaces of revolution on a work piece utilizing a tool of frustoconical form having cutting edges helically arranged on the peripheral surface thereof, the combination of means fortrotating said work piece and said tool in contact with their axes in the same plane and angularly related so that said tool contacts said surface in substantially line contact, and means relativelyfeeding said toolhaving contiguous singularly related surfaces of non-cutting position.

tion of said surfaces to throw chips away from said intersection, and means for rotating said tools.

13. A machine for finishing a work piece having a surface of revolution non-parallel to its axis comprising means for rotating said work piece at a speed above feeding speed, a. frustoconical cutter having cutting edges on its periph= eral surface, means for supporting said cutter in line contact with said surface so that the end of said cutter adjacent its large diameter contacts the portion of said surface closest to the axis of said work piece, and means for rotating said cutter.

14. A machine for finishing a rotary work piece having contiguous angularly related surfaces of revolution comprising means for rotating said work piece, a rotary tool in line contact with one .of said surfaces, said tool having cutting edges inclined to the direction of rotation such that each edge initiatesits out near the intersection of said surfaces to throw chips away from said intersection, and means for rotating said tool.

15. A machine for finishing a work piece having a surface of revolution comprising a frame,

a work support on said frame, a motor on said frame for rotating said work support, a tool carriage mounted on said frame for movement toward and from said work support, a tool support on said carriage, means for rotating said tool support, and feeding means for said carriage com rate of feed near depth to finish said work piece with fine cuts.

16. A machine for finishing awork piece having a surface of revolution comprising a frame,

a work support on said frame, a motor on said frame for rotating said work support, a tool car= riage mounted on said frame for movement to= ward and from said work support, a tool support on said carriage, means for rotating said tool support, and feeding means for said carriage comprising means for moving said carriage to=- ward said work support in plunge cutting relation, said last named means including a pain formed to cooperate with said tool carriage to reduce the rate of feed near depth to finish said work piece with fine cuts, to provide a suhstan tial dwell at depth, and to return said earnings to RQEBmT E. DRUND.

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