US3115729A

US3115729A - Centerles grinding machine

Info

Publication number: US3115729A
Application number: US251797A
Authority: US
Inventors: Elijah F Render
Original assignee: Cincinnati Milling Machine Co
Current assignee: Milacron Inc
Priority date: 1963-01-16
Filing date: 1963-01-16
Publication date: 1963-12-31
Anticipated expiration: 1980-12-31

Description

Dec. 31, 1963 E. F. RENDER CENTERLESS GRINDING MACHINE 5 Sheets-Sheet 1 Filed Jan. 16, 1963 Fig. 1

INVENTOR. ELIJAH F RENDER ATTORNEYS Dec. 31, 1963 E. F. RENDER CENTERLESS GRINDING MACHINE Filed Jan, 16, 1965 Fig.2

3 Sheets-Sheet 2 Dec431, 1963 E. F. RENDER CENTERLESS GRINDING MACHINE 3 Sheets-Sheet 3 Filed Jan. 16, 1963 United States Patent tion of Uhio 16, 1963, Ser. No. 251,797

Filed I an.

Claims. (Cl. 51-103) The present invention relates to a centerless grinding machine in which two workpieces can be ground simultaneously, and, more particularly, to a centerless grinding machine construction in which two workpieces are simultaneously urged in different directions in the grinding throat.

In the conventional centerless grinding machine, the grinding wheel and a regulating wheel opposite the grinding wheel define a grinding throat which has a blade therein to support a workpiece. The workpiece, during grinding, is rotated at a controlled rate by the regulating wheel for abrading contact with the rotating grinding wheel. In infeed centerless grinding, relative movement of the wheels away from each other permits unloading and loading of a workpiece in the throat, and relative movement of the wheels toward each other until the grinding throat is constricted to a predetermined size effects a grind on the workpiece in the throat to a predetermined diameter. In throughfeed centerless grinding, the wheels remain a fixed distance apart but the regulating wheel is tilted (at a small angle to a plane perpendicular to the top of the blade) to impart an axial component of force to a workpiece on the blade which moves the workpiece longitudinally, or endwise, through the grinding throat. The direction of tilt of the regulating wheel (relative to the plane perpendicular to the top of the blade) will determine the direction of the axial force component imparted to the workpiece, and hence the direction of movement of the workpiece on the blade.

Sometimes characteristics of these two grinding methods are combined in a grinding operation. For example, it is known to grind a workpiece by the infeed method but to tilt the regulating wheel as in throughfeed grinding to urge the workpiece axially against an end stop for precise axial location of the workpiece in the grinding throat.

In either infeed grinding or throughfeed grinding, two workpieces in end to end relationship can be ground simultaneously if the wheels are wide enough to accommodate two workpieces therebetween simultaneously. A more difificult problem is encountered, however, in simultaneously grinding two workpieces in an infeed grinding operation where tilt of the regulating wheel is desired to assure precise axial positioning of the workpieces, particularly where one end of the workpiece, because of its shape, must remain outside the grinding throat.

In the present invention, a simple construction is provided by which two workpieces are urged axially by the regulating wheel in different directions in the grinding throat. With this construction, two workpieces, each, for example, having a head which must remain outside the grinding throat, can be both urged in axially different directions toward an end stop centrally located in the throat for simultaneous grinding. In brief, the two workpieces are supported by two blade sections in end to end relationship, and the two blade sections are inclined at a small angle in opposite directions with respect to the axis of the regulating wheel. Thus the regulating wheel is tilted in one direction with respect to a plane perpendicular to the top of one blade section to urge one workpiece in one direction but is tilted in the opposite direction with respect to a plane perpendicular to the top of the other blade section to urge the other workpiece in the other direction. Although different sections of the regulating wheel rotate the two workpieces, the regulating wheel sections rotate about a common axis and therefore only a single regulating wheel housing and spindle is required.

It is therefore one object of the present invention to provide mechanism for the simultaneous infeed grinding of two workpieces in which the two workpieces are urged in different directions in the grinding throat for precise location therein.

It is another object of the present invention to provide mechanism for the simultaneous infeed grinding of two workpieces in which the two workpieces are urged in different directions against a central stop member in the grinding throat.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings, forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings:

FIG. 1 is a plan view of a centerless grinding machine incorporating the mechanism of the present invention;

FIG. 2 is an enlarged view taken on the line 22 of FIG. 1;

FIG. 3 is a view taken on the line 3-3 of FIG. 1;

FIG. 4 is an enlarged View taken on the line 4-4 of FIG. 3 with the angular relation between the tops of the blade sections and the regulating wheel sections somewhat exaggerated for clarity;

FIG. 5 is a view taken as the view of FIG. 4 showing the same angular relation between the tops of the blade sections and the regulating wheel sections, but with the axis of the regulating wheel sections and the tops of the blade sections at angles relative to the horizontal different than the angles shown in FIG. 4.

There is shown in FIG. 1 a plan view of a centerless grinding machine having a base 10 and having a grinding wheel spindle 11 rotatably mounted in the base 10 to carry, inside housing 12, a grinding wheel 13 for rotation about an axis A which is fixed relative to the base.

Mounted on the base 10 is a lower slide 14 which is normally clamped to the base 10 but which is adjustable, when the clamp (not shown) is released, towards and away from the grinding wheel. The lower slide 14, which extends away from the grinding wheel 13, has an upper slide 15 mounted thereon. A screw 16 is journaled in the base and is threadedly engaged with a nut (not shown) in the upper slide so that rotation of the screw 16 moves the upper slide on the lower slide, towards and away from the grinding wheel, when the lower slide is clamped to the base. By clamping the upper slide to the lower slide, and unclamping the lower slide from the base, the lower slide can be moved for set up adjustment by rotation of screw 16. Rotation of screw 16 is efiected through handwheel 17, bevel gear 18 fixed on the handwheel shaft, and bevel gear 19 fixed on screw 16.

Upper slide 15 has a vertical surface 20, facing the grinding wheel, on which is mounted a regulating wheel housing 21. The regulating wheel housing, when bolts 22 are loosened, can be swiveled on vertical surface 20 about pivot pin 23 and axis B thereof. The regulating wheel housing 21 has a single spindle 24 journaled there in which carries thereon a regulating wheel, indicated generally at 25, for rotation about the central axis C of the spindle 24. As shown best in FIG. 2, the lower slide has a workpiece support frame 26 secured thereon in which a workpiece support blade, indicated generally at 27, is tightly held by set

screws

28a and 28b.

The support blade 27 comprises two

blade sections

27a, 27b which may be connected, or integral, but preferably constitute separate, spaced apart, sections. In either case, each section supports one of the workpieces 30a, 39b in the grinding throat, or zone, 29 between the grinding and regulating wheels and defined thereby. The grinding wheel 13 and the regulating wheel 25 each may be considered as comprising two sections, 13a13b and 2-5a25b, respectively, one section for each workpiece supported in the throat. Similarly, the grinding throat 29 may be considered as comprising two sections 2%, 2%, each section to receive one of the two workpieces which are simultaneously ground. The sections of either te grinding wheel or the regulating wheel, or both, can be joined (that is, integral) or spaced apart, but, in either case, the grinding wheel sections are mounted on a common grinding wheel spindle (that is, spindle '11) and the regulating wheel sections are mounted on a common regulating wheel spindle (that is, spindle 2,4). For illustrative purposes, the regulating

wheel sections

25a, 25b are shown spaced apart while the grinding wheel sections 13a, 1312 are shown joined.

The

blade sections

27a, 27b are positioned in the grinding throat 29 (or, more specifically, in the grinding throat sections 29a, 295, respectively) in end to end relation, each extending longitudinally across one of the regulating wheel sections and one of the grinding wheel sections and positioned therebetween. The tops of both blades slope laterally toward the regulating wheel and, when the regulating wheel is properly adjusted relative to the blade (by adjustment of the upper slide relative to the lower slide) the workpieces 30a and 3012 are supported, in end .to end relation, by the regulating wheel sections and blade sections for movement toward the griding wheel for grinding, and for movement away from the grinding wheel for unloading finished parts and loading of new workpieces.

'The

workpieces

30a and 30b shown for illustrative purposes each have a

longitudinal axis

31a, 31b. The workpieces have a head (32a, 32b) at one end which will not fit within the throat, and a cylindrical shank (33a, 33b) which must be precisely positioned longitudinally in the throat for grinding. A stop member 34 is mounted on the lower slide 14 and extends through the workpiece support frame 26 to provide two opposite facing

abutment surfaces

34a, 34b. For precise positioning in the grinding throat sections, the workpieces must be continuously urged against'the stop member, that is, as viewed in FIG. 2, the workpiece 30a must be urged axially to the right against abutment surface 34a and the workpiece 30b must be urged axially to the left against abutment surface 34b.

If the regulating wheel lies parallel to a plane normal to the axis of a cylindrical workpiece, and the surface of the regulating wheel which is engaged with the workpiece at any instant moves perpendicularly to the longitudinal axis of the workpiece (that is, the surface of the regulating wheel moves perpendicularly to the line extending longitudinally on the top of the blade across the regulating wheel which defines the line of contact between the workpiece and the blade) there will be no axial force component transmitted to the workpiece by the regulating wheel. If, however, the regulating wheel lies at a small angle to a plane perpendicular to the longitudinal axis of the workpiece so that the surface of the regulating wheel in contact with the workpiece at any instant is moving at a small angle to a plane perpendicularto the workpiece axis and the line of contact between the workpiece and the blade, the workpiece is subjected to an axial force component by the regulating wheel, the axial force component acting in a direction depending on the direction of tilt of the regulating wheel from the plane perpendicular to the workpiece axis. This principle is known and utilized in many throughfeed and infeed grinding operations, and it is customary to tilt the regull lating wheel by swiveling the regulating wheel housing on the upper slide to tilt the spindle of the regulating wheel at a small angle to the top of the blade. In infeed grinding, a tilt of /2" will produce an endwise force compo nent to hold the workpiece against an end stop for location during the grind.

However, to grind the two

workpieces

30a and 30b imultaneously, and to urge these workpieces simultaneously against the

abutment surfaces

34a, 34b, it is necessary to urge the workpieces in different directions in the throat. This is accomplished with a single regulating wheel spindle 24.

As shown in FIG. 4 both regulating wheel sections lie parallel to a plane perpendicular to the axis C of the regulating wheel spindle 24, and the regulating wheel housing is adjusted on pin 23 to hold the axis C of spindle 24 horizontal during grinding. The supporting surface of blade section 27a, as it extends longitudinally across the regulating wheel section 25a as viewed in FIG. '4, is inclined longitudinally at an angle a in one direction (clockwise) from the horizontal (and hence from the spindle axis C). Thus, the surface of each regusection 217b, as it extends longitudinally across the regulating wheel section section 2511 as viewed in FIG. 4, is inclined longitudinally at the angle a in the opposite direction (counterclockwise) from the horizontal (and hence from the spindle axis C). Thus, the surface of each regulating wheel section in contact with a workpiece at any given instant (moving as indicated by arrows E) produces a resultant force F on the workpiece which can be resolved into a component F1 acting perpendicularly to the axis of the workpiece (and perpendicularly to the line on the supporting surface of the blade which defines the line of contact between the blade and the workpiece), and a component F2 acting axially (or longitudinally) on the workpiece. The axial force components F2 urge each workpiece in the throat endwise gainst the end stop member 34.

In FIG. 5, the

regulating wheel sections

25a, 25b are mounted on the single spindle 24 as in FIG. 4, and the regulating wheel sections bear the same relation to the blade sections and workpieces supported thereon, although all are positioned diiferently than in FIG. 4. With the machine set .as shown in FIG. 5, the regulating wheel spindle, and axis C thereof, is tilted at an angle a counterclockwise from horizontal line H. The top of blade section 270 as it extends longitudinally across the regulating wheel section 25a is horizontal (and thus is inclined longitudinally at an angle 0: clockwise from the spindle axis C). The top of blade section 27b is at an angle 2a counterclockwise from the horizontal line H (and thus is inclined longitudinally at an angle on counterclockwise from the spindle axis C). As in the embodiment of FIG. 4, a force F is exerted on each workpiece by the surface of the respective regulating wheel sections which may be resolved into force components F1 acting perpendicularly to the axis of the workpieces and force components F2 acting along the axis of the workpieces. As in the embodiment of FIG. 4, the axial force components F2, because of the diiferent relationship of the two blade sections to the two regulating whee-l sections, act in different directions (that is, to the right on workpiece 30b and to the left on workpiece 30a) to urge both workpieces simultaneously against the stop member 34.

The angles a and 20: may for example, be /2 and 1, respectively. At these small angles, the effect of gravity on the workpieces, compared to the axial forces produced thereon by the regulating wheel sections, is negligible.

The stop member 34 has a fluid passage 35 with oppositely extending branch passages 35a and 355 which terrrninate, respectively, at

abutment surfaces

34a and 34b. Passage 35 is connected to passage 36 in the lower slide, which is connected to an air pressure line 37 supplied by a source 38 of air under pressure. Line 37 contains a shut-01f valve 39 which is closed during grinding, but

which is opened after the grind is completed and the Wheels are separated, to propel the workpieces in opposite directions for ejection from the grinding throat.

In any centerless grinding operation, it is desirable that the grinding and regulating wheels make line contact with the workpiece. If, in truing the wheel, a truing tool is moved along a straight line parallel to the axis on which a workpiece will lie during grinding, the wheel will be shaped for line contact with the workpiece. If the workpiece is to lie parallel to the axis of rotation of the wheel, the wheel'wi'll be formed to a perfect cylinder. If, however, the workpiece is to lie at a small angle to the axis of the wheel, the wheel will be trued with the periphery defining a slightly concave arc. If the truing tool does not move parallel to the axis on which the workpiece is to lie for grinding, the proper shape can neverthless be imparted to the wheel by means of a cam, in a manner well known to those skilled in the art of centerless grinding.

In the present invention, the workpieces are not in perfeet alignment since each is inclined differently with respect to the axis C of the regulating wheel, and this relative inclination must be taken into account when truing the regulating wheel and the grinding wheel. The grinding wheel truing mechanism, indicated generally at 40, has a slide 41 movable longitudinally (parallel to axis A of the grinding wheel) along ways 42 on the base 169 by rotation of handwheel 43 which is connected to a screw 44 journaled in the base and threadedly engaged with slide 41. A cross slide 45 is slidably received in slide 41 and has a follower 46 connected thereto and depending into engagement with a cam 47 mounted on the base. Cam 47 comprises two

cam sections

47a and 47b, each aligned with one grinding wheel section, and when the truing slide 41 is moved across the grinding wheel by handwheel 43, slide 45 is moved towards and away from the grinding wheel in accordance with the shape of the cam sections. Cross slide 45 carries a diamond 48 at its inner end which shapes the respective wheel sections in accordance with the respective cam sections. Each cam section can be adjusted on the base independently of the other cam section to permit adjustment of one or the other as sizing of workpieces ground in the respective grinding throat sections may indicate to be necessary. With the two cam sections, each section of the grinding wheel can be trued to the appropriate shape to assure line contact of each section with one of the workpieces in the grinding throat regardless of the different orientation of the workpieces.

A truing mechanism 49 is mounted on the regulating wheel housing for truing the regulating wheel. This mechanism, like the grinding wheel truing mechanism, has two cam sections 50a, 50b to permit truing the two regulating wheel sections to the required shape for line contact with the respective workpieces. The cam sections are mounted on the regulating wheel housing and as the truing mechanism is moved across the regulating wheels, by handwheel 51, the cross slide 52, having a diamond at its inner end, moves towards and away from the regulating wheel in accordance with the shape of the cam sections.

What is claimed is:

1. In a centerless grinding machine for simultaneously grinding two workpieces each having a longitudinal axis, said grinding machine having a rotatable grinding wheel and having a regulating wheel rotatable about an axis opposite the grinding wheel to define a grinding throat between the grinding wheel and the regulating wheel, the improvement comprising a pair of workpiece blade sections extending longitudinally across the regulating wheel in end to end relationship in the grinding throat to support two workpieces therein for rotation about their axes by the regulating wheel, the tops of said blade sections being longitudinally inclined in opposite directions with respect to the axis of the regulating wheel to position the workpieces thereon relative to the regulating wheel for application to the workpieces by the regulating wheel as the regulating wheel rotates of oppositely acting axial force components urging the workpieces in difierent directions in the grinding throat.

2. In a centerless grinding machine for simultaneously grinding two workpieces each having a longitudinal axis, said grinding machine having a rotatable grinding wheel and having a regulating wheel rotatable about an axis opposite the grinding wheel to define a grinding throat between the grinding wheel and the regulating wheel, the combination comprising a pair of workpiece blade sections extending longitudinally across the regulating wheel in end to end relationship in the grinding throat to support two workpieces therein for rotation about their axes by the regulating wheel, the tops of said blade sections being longitudinally inclined in opposite directions with respect to the axis of the regulating wheel to position the workpieces thereon relative to the regulating wheel for application to the workpieces by the regulating wheel as the regulating wheel rotates of axial force components urging the workpieces together in the grinding throat, and means defining oppositely facing abutment surfaces for locating engagement by the inner ends of the respective workpieces.

3. In a centerless grinding machine for simultaneously grinding two workpieces each having a longitudinal axis, the combination comprising a rotatable grinding wheel, a regulating wheel having two sections rotatable about a common axis opposite the grinding wheel to define with the grinding wheel a grinding throat, a pair of workpiece blade sections extending, respectively, longitudinally across the regulating wheel sections in end to end relationship in the grinding throat to support two workpieces therein for rotation about their axes by the regulating wheel sections, respectively, the tops of said blade sections being longitudinally inclined in opposite directions with respect to the common axis of the regulating wheel sections to position each workpiece relative to the regulating wheel section by which it is rotated for application to the workpiece by the regulating wheel section as the regulating wheel section rotates of an axial force component urging the workpiece toward the center of the grinding throat, and a stop member in the center of the grinding throat between the workpieces having oppositely facing abutment surfaces for locating engagement by the inner ends of the workpieces, respectively.

4. In a centerless grinding machine for simultaneously grinding two workpieces each having a longitudinal axis, the combination comprising a grinding wheel having two sections rotatable about a common axis, a regulating wheel having two sections rotatable about a common axis opposite the grinding wheel sections, respectively, to define with the grinding wheel sections a grinding throat having two grinding throat sections, a workpiece blade haying two sections extending, respectively, longitudinally across the regulating wheel sections in end to end relationship in the grinding throat sections, respectively, to support a workpiece in each grinding throat section for rotation about its longitudinal axis by the regulating wheel section of the grinding throat section, the top of the blade in one grinding throat section being inclined longitudinally relative to the common axis of the regulating wheel sections oppositely to the top of the blade in the other grinding throat section to position each workpiece relative to the regulating wheel section by which it is rotated for application to the workpiece by the regulating wheel section as the regulating wheel section rotates of an axial force component urging the workpiece toward the center of the grinding throat, a stop member in the center of the grinding throat between the workpieces having oppositely facing abutment surfaces for locating engagement by the inner ends of the workpieces, means in the stop member to propel the workpieces apart for ejection, and means to true different contours on the wheels of the respective throat sections to establish line contact with the workpieces mounted on the oppositely longitudinally inclined blade sections.

5. In a centerless grinding machine for the simultaneous infeed grinding of two workpieces each having a longitudinal axis and a head at one end, the combination comprising a grinding wheel having two sections rotatable about a common axis, a regulating wheel having two sections rotatable about a common axis opposite the grinding wheel sections, respectively, to define with the grinding Wheel sections a grinding throat having two grinding throat sections, a workpiece blade having two sections extending, respectively, longitudinally across the regulating wheel sections in end to end relationship in the grinding throat sections, respectively, to support a workpiece in each grinding throat section for rotation about its longitudinal axis by the regulating wheel section of the grinding throat section, the top of the blade in one grinding throat section being inclined longitudinally relative to the common axis of the regulating wheel sections oppositely to the top of the blade in the other grinding throat section to position each workpiece relative to the regulating wheel section by which it is rotated for application to the workpiece by the regulating wheel section as the regulating Wheel section rotates of an axial force component urging the workpiece toward the center of the grinding throat, a stop member in the center of the grinding throat between the workpieces having oppositely facing abutment surfaces for locating engagement by the inner ends of the workpieces, said stop having fluid passages terminating at the abutment surfaces to propel the workpieces apart for ejection, a truing mechanism for the grinding wheel and a truing mechanism for the regulating wheel, each truing mechanism having a carn section for each wheel section to true different contours on the wheels of the respective throat sections to establish line contact with the workpieces mounted on the oppositely longitudinally inclined blade sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,816,171 Booth July 28, 1931 2,023,720 Asbridge Dec. 10, 1935 2,743,555 Irvine May 1, 1956 2,855,729 Render Oct. 14, 1958 2,863,263 Perkes et al Dec. 9, 1958 2,939,253 Richards et al June 7, 1960 2,952,953 Livingston Sept. 20, 1960 2,971,297 Hakanson Feb. 14, 1961 Patent No 3,,115,729 December 31,, 1963 Elijah F. Render It is hereby certified that er ent requiring correction and that t corrected below.

ror appears in the above numbered pathe said Letters Patent should read as Column 4,, line 22, for "from the spindle axis C) Thus the surface of each regu-". read from spindle axis C) o and the supporting surface of blade Signed and sealed this 9th day of June 1964,

(SEAL) Attest:

ERNEST W; SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents

Claims

1. IN A CENTERLESS GRINDING MACHINE FOR SIMULTANEOUSLY GRINDING TWO WORKPIECES EACH HAVING A LONGITUDINAL AXIS, SAID GRINDING MACHINE HAVING A ROTATABLE GRINDING WHEEL AND HAVING A REGULATING WHEEL ROTATABLE ABOUT AN AXIS OPPOSITE THE GRINDING WHEEL TO DEFINE A GRINDING THROAT BETWEEN THE GRINDING WHEEL AND THE REGULATING WHEEL, THE IMPROVEMENT COMPRISING A PAIR OF WORKPIECE BLADE SECTIONS EXTENDING LONGITUDINALLY ACROSS THE REGULATING WHEEL IN END TO END RELATIONSHIP IN THE GRINDING THROAT TO SUPPORT TWO WORKPIECES THEREIN FOR ROTATION ABOUT THEIR AXES BY THE REGULATING WHEEL, THE TOPS OF SAID BLADE SECTIONS BEING LONGITUDINALLY INCLINED IN OPPOSITE DIRECTIONS WITH RESPECT TO THE AXIS OF THE REGULATING WHEEL TO POSITION THE WORKPIECES THEREON RELATIVE TO THE REGULATING WHEEL