US2293327A - Grinding machine - Google Patents

Description

Aug. 18, 1942 M. H. ARMS E.TA L

GRINDING MACHINE Filed Dec. 22, 1939 2 Sheets-Sheet; l

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W M W1 Patented Aug. 18, 1942 2,293,327 GRWDING ew-WE Merton H. Arms and Albert Tu rner, Springfield,

,V t., assignors, to Bryant Chucking Grinder Company,, Springfield, Vt., a corporation of Vermont Application December 22, weasel-n1 No. 310,514 7 claims. (01. ies-11y This invention relates to grinding machines, and'rmore particularly to those designed to grind otherthan axiallyiofthe work, and where the grindingqwheel is. moved in an arcuate path for fe,eding.- ,In machines of this character the surface contact of the ground work is determined,- vat :leastin part, by the contour dressed on the Wheel, and a variation in wheel diameter may result in a slight wheel contour variation. This invention, therefore, has for an object to avoid -this. slightwheel contour variation, and, this is done in accordance with this invention by: truing Loft axially rather thanradially; so that thezdiameterof the wheel is not changed by .the truing action. It should be understood, however, that this method of truing can be usedwhether or not the wheel is so ground that a reduction in diameter of the wheel bytruing would result in inaccuracies. In some cases: this axial: truing requires endwise truing also, in order that the. activewheel contour may bekept sufficientlyinear to that'end of the wheel fromwhich itotherwise would recede to properly clearrother parts of the work or of the machine; .For a. more complete understanding of this invention, reference may be had to the accompanying drawings, in which Figure his a side: elevation of a two wheel internal grinding machine embodying this invention. 1 r

,Figures 2 and 4 are detail sectional views to a larger. scale on lines 2-2 and 4-4, respec-* tively, of Figurelr- I l n Figure 3' is a detail sectional view showing thezmanner in which the wheel-for taper grind ingmayloetrued.v 1 I .Figure 5 is a detail section to a larger scale on line-5+5 of Figure 4. i A

Figuret6 is a somewhat diagrammatic detail showing of. one of the wheel-controlling feed cams. 1r

Figure 7 is a detail in perspective showing a modified construction of wheel iend trimming mechanism.r.. .v v m .,Figure;;8';is a fragmentary section through a the diameter of the wheel is grinding. wheel showing-the usual method of and 4 support for axial and rocking motion a bar 5 on which is mounted a rock arm 6. While' as'shown in the Arinspatent hereinb'efore men-' tioned, the arm supports 'a single grinding wheel,

two such grinding wheels shown at I and 8 are shown as carried by this arm in the accompanying drawings. It should be understood, however, that this inventionis' also applicable to a machine having a single grinding" wheel or more than two. The arm '6 is mounted for motion parallel to its axis to bring the grinding wheels into operative relation to the work, the wheel 8 beingthere illustrated in Figure 2, the workbeing indicated at" 10. As shown the face I I of the work is ground at an angle to the axis. of the grinding wheel and a truing diamond l2 in a stationary holder Isis arranged to true the wheel face Ila to the contour desired for this face ll. This"truing device is arrarigedat one side of the line of axial motion of the'wheel and the arm 6 is swung about the axis of the bar 5 in order to bring either of the wheels selected into truing relation to the truing device. Due to this angular motion of the arm 6 the. engagement of the truing device on the wheel is slightly dil ferent with different wheel diameters so that should the wheel be trued away in a manner to decrease its diameter, a

wheel contour which would be correct when thewheel .is of a relatively larger diameter would be trued slightly incorrectly when the wheel is of a small diameter. This is due to the difierences in angular'position of the arm 6 when truing is effected for large and'small diameter wheels and the consequent variation in the point of application of the truing device with respect to the axis of the wheel. l

The manner of truing is shown by the dotted line :aa of Figure 3, the face i la. being trued back from the full line position shown toward this dotted line position without decrease of wheel diameter for the corresponding portions of the trued length. This may be compared with thedotted line bb of Figure 8, showing the former method of'truing the wheel face to the contour variation is too small to be indicated on. the drawings but prevents obtaining the high accuracy often required in ground work.

The mechanism for supporting the arm 6 and controlling it for presentation and operation of either selected wheel on the work forms no part of the present invention, but forms the subject matter of a co-pending application of one of the present applicants.

In so far as this invention is concerned, it is sufficient to state that the truing of both wheels is effected by the same truing tool and by similar control means, the shape of the former cam for each wheel being suitable for the desired contour of the respective wheel to produce the desired work face contour.

In order to produce the desired angular work and wheel faces, the wheel is caused to traverse the truing device while at the same time the arm 6 is given an angular motion. This motion of the arm 6 angularly as it is moved axially is determined by a cam. Such a cam for the grinding wheel 8 is shown in Figure 6. This cam I is carried at the lower end of a bracket l6 secured to the lower end of the arm 6 and bears against a roller journaled in an axially movable but non-rotatable feed shaft l3. This feed shaft has secured therein a portion l9 threaded into a rotary nut 20, this nut being turnable by a feed wheel 2| in the manner shown in the Arms patent to which reference has heretofore been made. This cam I5 is shown as made in two parts 23 and 24, the part 23 having a high point 25 and a low point 26, while the part 24 has a high point 27 and a low point 28. The slope between the points 25 and 2S determines the swing of the arm 6 as it is moved axially during the truing operation, while the slope between the points 21 and 28 determines the angular motion of the arm 6 during the :corresponding axial travel of the wheel 8 for the grinding operation. A similar cam shown at 30 and secured to the bracket l6 and arranged to ride against a similar feed roll 3| in a second feed mechanism determines the angular position and the angular extent of motion of the arm 6 when the wheel 1 is in operative position. As shown the feed roller 3| is arranged for axial adjustment through a screw and nut and the gears 33 and 34, a shaft 35 and a train of gears indicated generally at 36, from a second feed wheel 31 on the forward face of the machine. A vertically adjustable roller slide 33 may be engaged with either selected of a pair of stop members 39 or 39a at the outer end of the stroke of the wheel slide 6 to guide this slide with the cam l5 engaging the feed roller H or the cam 30 engaging the feed roller 3|, depending on which of the grinding wheels it is desired to have in operation at any one time. This adjustment of the roller slide and the corresponding angular position of the member 6 may be made by hand as desired. In the axial position of the slide 6 when this adjustment may be made, there is no interference from the feed mechanism carrying the roller 3|. The axial motion of the arm 6 may be produced by the power mechanism shown in the Arms Patent No.

2,176,985 or by any other suitable means. This arrangement of the two grinding wheels and the two feed wheels forms no part of the present invention.

In order that the truing operation shall not be effective to reduce the diameters of the wheels, provision is made, in accordance with this invention, for causing the truing action to progress axially rather than radially of the wheels. To this end (see Figure 5) each wheel is carried on a shaft such as 4|] mounted for rotation in a sleeve 4|. This sleeve 4| is provided with a threaded portion 42 on which is engaged an internally threaded nut 43. This nut is held from axial motion, engaging at one end face against one end of a bearing bushing 44 and at its other face against a ballbearing 45, in turn engaged by a cover member 46, which is secured to the bracket 6 as by suitable bolts 41 (see Figure 4). The nut is provided with worm teeth on its outer face as at 48, with which engages a worm 49 on a shaft 59. The shaft 50 is extended from the casing 46 to the front of the machine where it has attached thereto a hand wheel 5| by which it may be turned. Both of the grinding wheels are similarly mounted, it being evident that by turning the hand wheel 5| the corresponding bearing sleeve 4| will be moved axially, thereby moving the corresponding grinding wheel axially with respect to the arm 6. Thus the active taper contoured portion of the grinding wheel is trued axially rather than radially, the Zone trued progressively moving further from the outer smaller diameter end of the grinding wheel as the truing takes place. It will be noted that by adjusting the grinding wheel axially relative to its support toward the smaller diameter end, the larger diameter end is brought toward the axial position of the taper truing tool so that the position of the rocking path of the wheel for truing may remain constant for each truing action. Thus the contour of the wheel is not changed due to varying angular positions of the wheel carrier for any given diameter of the tapered wheel face. Likewise, any given diameter portion of the wheel may be maintained at the same relation to the wheel holder regardless of the amount of truing by the axial adjustment of the wheel relative to its holder. As this action ultimately, however, might bring this smaller diameter end so far toward the work that it would interfere with either the work or the work holding mechanism, .provision may be made for removing this extended end portion of the wheel. To this end the truing device may have arranged in fixed relation thereto a suitable end truing device shown at 55 in Figure 3. While this may be of various types, this device is shown as a truing wheel journaled on a stud 56, the face of this wheel engaging the end of the grinding wheel and automatically keeping it always a predetermined distance axially from the edge 51 of the grinding wheel which defines the inner limit of the trued zone, the wheel slide or arm 6 being brought to a definite axial position as the rear corner of the trued contour of the wheel passes the truing tool. A stop rod 58 having abutment elements 59 which may be brought selectively into engagement with either of a pair of shoulders 590 and 59l of a sleeve 60 limits the extent to which the rock arm 6 may move toward the left. When either of these elements 59 is turned to make contact with the shoulder 590 the adjustment determines the limit of the grinding stroke for the corresponding grinding wheel, while when either element 59 engages the shoulder 59| the limit of motion is suitable for cutting back the end of the corresponding grinding wheel by member 55. Thus as the trued zone progresses back from the outer end of the grinding wheel, this end is removed so that at no time does the wheel extend sufliciently far beyond its active face to interfere with either the work or any portion of the grinding machine.

In Figure '7 there is shown an operator-actuated wheel end trimmer separate from the contour truing device. This may comprise an arm 6| having a handle portion 62 by which it may be rocked, and mounted on a rock shaft 63 journaled in a bracket 64 which may be secured to the machine frame in front of and below the work holder. The arm 6| carries a diamond truing tool 65 which may be moved across the end face of the wheel I or 8 by rocking this arm when the wheel slide or arm 6 is back from the work to a predetermined point as determined, for example, by the stop rod 58 as previously described. A spring 66 serves to take up any looseness of the shaft 63 in its supporting bracket 64, the spring engaging at one end on a tapered bushing (not shown) through which the shaft 63 passes and at its other end on a nut 61 threaded onto the rock shaft 63. When face grinding is desired, the diamond tool 65 might be preferable to the tool 55 shown in Figure 3, as it would be likely to produce a better cutting face on the wheel end. The arm 6| may :be rocked down toward the machine frame when use of this end truing tool is not desired.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from the spirit or scope of this invention as defined by the appended claims.

We claim:

1. In a grinding machine having a work holder, a grinding wheel, a grinding wheel holder relatively movable with respect to said work holder transverse to and lengthwise of the axis of said wheel, a truing device across which a portion of said wheel may pass during said relative motion of said wheel and work holders to true said portion to tapered contour, and means for adjusting said wheel axially relative to said wheel holder in accordance with the amount removed by wear and truing to maintain a definite diameter portion of said wheel in a predetermined relation to said wheel holder regardless of truing.

2. In a grinding machine having a work holder, a grinding wheel, a grinding wheel holder relatively movable with respect to said work holder transverse to and lengthwise of the axis of said wheel, a truing device across which a portion of said wheel may pass during said relative motion of said wheel and work holders to true said portion to tapered contour, means for adjusting said wheel axially relative to said wheel holder in the direction toward the smaller diameter to thereby adjust the axial position on the wheel of the portion trued and maintain a wheel portion of a certain diameter regardless of truing at a definite axial relation to said wheel holder, and means for removing an end portion of said wheel as said trued portion progresses away therefrom.

3. In a grinding machine having a grinding wheel holder, a grinding wheel axially adjustable relative to said holder, means for truing a face of said wheel to tapered contour, and means for adjusting said tapered wheel axially corresponding to the amount of truing to maintain a given diameter portion of said tapered face in a definite axial relation to said wheel holder regardless of the extent of truing.

4. In a grinding machine having a work holder, a grinding wheel holder relatively movable with respect to said work holder, a wheel truing mechanism comprising an edge truing tool and an end face truing tool, means for adjusting said grinding wheel axially with respect to its holder, and means for guiding said holders during their relative motions and with respect to said truing mechanism to true the wheel edge to a predetermined axial tapered contour and its end face to a predetermined relation to said axial contour and with a predetermined diameter portion of the wheel in the same axial relation to said wheel holder regardless of the amount of truing.

5. In a grinding machine having a work holder, a grinding wheel, a grinding wheel holder pivotally mounted to swing in a plane transverse to the axis of said grinding wheel toward and from work carried by said work holder, means for moving said wheel and work parallel to said wheel axis, a truing device across which said wheel may pass during such parallel motion, means for swinging said wheel holder during truing and grinding to dress the wheel to desired tapered contour and to cause the dressed face to grind a face of the work to desired tapered contour, and means for adjusting said wheel and dressing tool relatively axially of said wheel in the direction to bring the larger diameter portion of the wheel toward the dressing tool to cause the dressed tapered face of the wheel to progress axially of said wheel as it is dressed without reduction of wheel diameter at the corresponding portions of the length of the dressed face.

6. In a grinding machine having a work holder, a grinding wheel, a grinding wheel holder pivotally mounted to swing in a plane transverse to the axis of said grinding wheel toward and from work carried by said work holder, means for moving said wheel and work parallel to said wheel axis, a truing device across which said wheel may pass during such parallel motion, means for swinging said wheel holder during. truing and grinding to dress the wheel to desired tapered contour and to cause the dressed face to grind a face of the work to desired tapered contour, means for adjusting said wheel and dressing tool relatively axially of said Wheel in the direction to bring the larger diameter portion of the wheel toward the dressing tool to cause the dressed tapered face of the wheel to progress axially of said wheel as it is dressed without reduction of wheel diameter at the corresponding portions of the length of the dressed face, and means for removing the end face of said wheel from which said dressed face recedes as dressing continues to maintain said dressed face at a predetermined length.

7. In a grinding machine wherein a grinding wheel having a tapered periphery is moved from and toward the work and from and toward a truing wheel mechanism through an arcuate path, the method of preventing inaccuracies in the work due to variations in wheel diameter =whi1e truing, which comprises adjusting the wheel axially relative to the holder in the direction to,- ward its smaller diameter portion as it is trued-to maintain the same diameter portion of said wheel regardless of truing in the same axial relation to said holder, and controlling the relative motion of the work and said holder in the same manner in each grinding cycle regardless of wheel truing.

MERTON H. ARMS. ALBERT TURNER.

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