Apparatus for taper grinding elongated articles

Nov. 20, 1951

F. C. JULIAN

2,575,346

APPARATUS FOR TAPER GRINDING ELONGATED ARTICLES

Filed July 29, 1950 2 SHEETS—SHEET 1

<img file="US2575346A_D0001.tif" />

3n»entor

Fredrick C. Julian ” ^e- '^yKu^

Nov. 20, 1951 f. c. julian 2,575,346

APPARATUS FOR TAPER GRINDING ELONGATED ARTICLES

Filed July 29, 1950 -2 SHEETS—SHEET 2

<img file="US2575346A_D0002.tif" />

<img file="US2575346A_D0003.tif" />

8b

UNITED STATES PATENT OFFICE

Patented Nov. 20, 1951

2,575,346

2,575,346

APPARATUS FOR TAPER GRINDING ELONGATED ARTICLES

Fredrick C. Julian, South Bend, Ind., assignor to South Bend Tool and Die Co., Inc., South Bend, Ind., a corporation of Indiana .

Application July 29,1950, Serial No. 176,650

Claims.

This invention relates to improvements in grinding machinery, particularly to a modified centerless grinder, and to a method for taper grinding elongated work pieces.

Attachments for centerless grinders are known whereby the rate at which the work piece is urged through the grinding throat is synchronized with the .rate of change of the width of the throat to taper grind elongated rigid articles. Although certain of such heretofore known modified centerless grinders, and; the methods employing them, have been found reasonably satisfactory for taper grinding rigid articles, such as reasonably heavy steel and even wood rods, no modified centerless grinder nor any attachment therefor; has heretofore been described which is suitable for the automatic and accurate tapering of rods characterized by a.relativelylow degree of rigidity or stiffness coupled with considerable toughness. When it is attempted to use the heretofore known modified centerless grinders, wherein the work piece is invariably urged, at least in part, through the grinding throat by pressure applied to its end, for tapering long rods having these characteristics, the rod invariably buckles and accurate grinding to a desired taper is impossible. This is true of long metal rods of small diameter and particularly of plastic rods and plastic rods reenforced with glassfibersor glass threads, such as those used in the making of fishing rods, golf club handles and the like.

In an attempt to overcome these difficulties, it has been the practice in the past when tapering relatively limber rods, such as those just mentioned, to adjust the control wheel of the centerless grinder to provide a feed component to draw the work piece through the grinding throat and then to operate the throat adjusting mechanism of the grinder manually. It is apparent that such a procedure can lead only to erratic and inconstant results with no two. ground articles being more than approximately identical. This procedure also results in a high proportion of, rejects due to inadvertant and excessive removal of stock. If, in an attempt to avoid an. excessive removal of stock, an insufficient amount of stock is removed during? _a given pass? of the rod blank through? the grinder, it must be rerun and this can often be done only after· considerable testing and measuring to determine just where? the additional stock must be removed. It is apparent that an apparatus and a method whereby limber elongated blanks· of metal or resinous materials and other flexible but toughcompositions can be ground rapidly, economically

DI. 51—103) and accurately to a desired taper and without the exercise of an undue amount of skill on the part of the operator would be of great value;

It is, therefore, an Object of the present ini vention to provide apparatus and a method for taper grinding elongated articles characterized by their flexibility and toughness.

An additional object is to provide apparatus and a method for grinding elongated plastic and 0 glass fiber reenforced plastic rods automatically and accurately to a desired longitudinal taper;

An additional object is to provide an attachment for a centerless grinder whereby the latter can be used for the substantially· automatic and 5 accurate taper grinding of elongated articles characterized by their flexibility and toughness.

An additional object is to provide apparatus for taper grinding elongated articles capable of adjustment to accommodate work pieces of differ0 ent lengths.

According to the present, invention, these and related objects are accomplished readily and economically by equipping, a substantially , conventional centerless, grinder with a cam mech;5 anismfor advancing the regulating wheel thereof to control the width of the grinding throat and providing a driving means for the cam having an adjustable speed control, which? is synchronized with the rate of travel of the work ₀ piece through the grinding throat, the travel of the work piece, being caused substantially entirely by a feed component of the regulating wheel. To. reduce the operative skill· necessary and to enable the rate of cam. travel to be set to synchronize _s accurately with the rate of travel of the -work piece, a. work follower is provided which either contacts'lightly. or follows closely at a substantially constant distance the end of the work piece and which, is actuated in? synchronism with the travel of the cam. A follower adjusting means is provided, to adjust the. ratio; of the total travel of the cam to the total travel of the follower to accommodate work pieces.of different lengths. It is to be noted that the work piece, follower at? na time assists. materially in forwarding the work piece through the.grinding throatin operating the apparatus,, the regulating wheel is first adjusted to provide? a feed component suitable for the particular kind of work piece being operated upon. The rate of travel of the piece through the throat remains substantially constant for separate work pieces having the same diameter and composition for any given feed component of the regulating wheel. The follower adjusting means is then adjusted to

2,675.346 provide for a total travel of the work follower equal to the length of the taper desired on the work piece for each complete travel of the cam. The follower thus serves as a visual indicator of the rate of travel of the cam and hence of the rate of change in the width of the grinding throat with respect to the rate of travel of the work piece through the throat. By adjusting the speed of travel of the cam and work follower so that the latter moves at the same speed as the work piece, it is assured that the travel of the cam coincides in time with the travel of the work piece though the grinding throat and that the contour as determined by the cam surface is thus “spread” along the desired section of the work piece in the same longitudinal proportions as it appears on the cam. When a different taper or contour is desired, a correspondingly differently formed cam is inserted in the machine.

With a properly formed cam installed in the machine and with the total travel of the work follower adjusted to accommodate the length of the work piece being operated upon, it is merely necessary to forward a few test pieces through the grinder and adjust the rate of travel of the cam, and therefore of the work follower, until the follower moves at substantially the same speed as the work piece. Subsequent pieces can then be forwarded through the grinder rapidly and in quick succession with the production of substantially identical tapered articles with only occasional adjustment of the speed of the cam and work follower being required.

The invention can be best understood by reference to the accompanying drawing wherein there is shown one modification of the apparatus of the invention, certain of the parts being shown on a somewhat exaggerated scale for the sake of clarity, and wherein:

Figure 1 is an oblique view of a centerless grinder equipped with an attachment embodying features of the invention,

Figure 2 is a partial sectional elevation taken along the. line II—II of Figure 1,

Figure 3 is a plan view, partly in section and rotated 90 degrees counter clockwise, taken along the line HI—III of Figure 2, and . Figure 4 is a schematic view of an hydraulic system for operating certain of the parts.

In the drawing, the bed 11 of a centerless grinder has mounted thereon a journal 12 for the spindle of a grinding wheel 13 which can be rotated at a high grinding rate of speed in a clockwise direction for grinding the work piece. The bed ί I also supports a sliding bed member 14 on which is mounted for movement therewith and for relative movement thereto a regulating wheel unit designated, generally, by the reference numeral 15. The regulating wheel unit 15 has mounted thereon, conventionally by means of a suitably swiveled bracket or its equivalent (not shown), a head 16 in which is journaled the spindle 17 of a regulating wheel 18 rotatable at a relatively slow work-controlling rate of speed in a clockwise direction. By adjustment of the swiveled bracket the regulating wheel can be positioned to give it a desired feed component for the work piece. The operative faces of the grinding and regulating wheels are separated from one another to form a grinding throat therebetween. Beneath the grinding throat there is positioned a work rest blade 19 secured to the sliding bed member 14 by means of a conventional work fixture or in any other suitable manner. The upper or operative surface 22 of the work rest blade is preferably flat although it may in some instances be inclined downwardly in the general direction of the operative surface of the regulating wheel 18.

The bed member 11 has secured thereto at its end opposite the grinding wheel ί 3 a pair of laterally extending supporting arms or members 23 and 24 with their top surfaces conveniently substantially continuous with the top of the bed 11. Each of the supporting arms 23 and 24 is conveniently formed and supported by welding one end of a suitable channel member of suitable length perpendicularly to one side of a plate 25 and securing the plate with stud bolts 27 along the upper edge of one side of the bed. For purposes of differentiation, the laterally extending supporting members 23 and 24 are, for reasons which will be apparent, herein sometimes referred to as a “pivot race supporting member” and a “cam drive supporting member,” respectively, it being understood that the former is on the side of the bed 11 from which the work piece enters the grinding throat and the latter is on the opposite side. A suitable brace 26 extending between the bed 11 and the pivot race supporting arm 23 can be provided to hold the latter securely in place without springing.

A fulcrum supporting member 28 is also provided near the outer end of the pivot race supporting member 23 and may conveniently be a longitudinal member, such as a channel, welded or otherwise secured against the lower surface of the pivot race supporting member 23 and extending perpendicularly therefrom in a direction away from the normal position of the work piece support hereinafter described. Suitable piers 29, 32 and 33, or other suitable supporting members, are provided to insure a suitable degree of rigidity of the supporting members 23, 24 and 28.

In the modification shown providing for an hydraulic drive for certain of the members, a suitable hydraulic drive cylinder 34, fitted with conduits 35 and 36 for admitting and venting an hydraulic fluid, is secured near the outer end of the upper surface of the cam drive supporting member 24 in a position substantially longitudinally parallel therewith. The hydraulic drive cylinder 34 contains a piston (not shown) and a piston rod 37 adapted to travel longitudinally in fluid-tight relationship through a suitable port and stuffing box in the end plate 31 of the cylinder 34 nearest the bed II, the conduits 35 and 36 being arranged so that the piston and piston rod 37 can be urged in either direction. The hydraulic system for driving the piston will be described in detail hereinafter.

A pivot race member, indicated generally by the reference numeral 38, is secured near the outer end of the upper surface of the pivot race supporting member 23. In the modification shown, the pivot race member 38 consists of an elongated channel member 39 positioned with the channel in its upper surface longitudinally parallel with the pivot race supporting arm 23, and a pair of elongated pivot slide retaining plates 42 mounted on the top of the sides of the channel member 39, each extending laterally a short distance over the channel so as to retain slidably within the channel an inverted T-shaped pivot slide 43. A series of bolts 44 pass through registering holes in the pivot slide retaining plates 42 and the channel member 39 and threadably engage the pivot race supporting arm 23. The pivot slide 43 is of sufficient vertical thickness so that its upper surface is in a plane which clears

2,575,346 the upper surfaces of the pivot slide retaining plates 42 and the heads of the bolts 44. An upwardly projecting circular pivot pin 45 is mounted on the upper surface of the pivot slide 43.

The pivot slide 43 is secured at its end nearest the bed li by a suitable connector 46, such as a yoke and pin, to one end of a spacer rod 47 which is in turn connected at its other end by another suitable connector 48 to one end of an elongated plate cam 49. The other end of the cam 49 is connected by a suitable, connector, 50 of Figure 3, to the exposed end of the piston rod 37. The piston rod 37, the plate cam ¢9, the spacer, rod 47 and the pivot slide. 43 thus form; a longitudinally rigid assembly capable of longitudinal travel in either direction in response to pressure of hydraulic fluid on the piston within the cylinder 34. An adjusting means, such as a threaded connection and lock nut 52, is preferably provided for making minor adjustments in the effective length of the spacer rod 47. Suitable adjusting means can also be provided between the cam and the piston rod.

The cam 49 is formed, in the modification shown, with the cam surface 53 on its edge nearest. the. regulating wheel unit i 5, its opposite edge 51 being a planar cam guiding surface. Also, in the modification shown, the cam plate is narrower at its end connected to the piston rod 37 than at its. other end, the regulating wheel I 8 traveling toward the grinding wheel 13 during the forward travel of the cam 49 toward the hydraulic cylinder 34.: It will be apparent as the description proceeds, however, that cams can be used in which the relationships of the end widths and of the edges are reversed or otherwise varied from those just described, sometimes with a reversal of the direction of travel of the cam causing a forward travel of the regulating wheel.

The cam member 49, during its longitudinal travel, actuates a cam responsive slide member 54 which is adapted to slide in a plane normal to the line of travel of the cam and which is connected rigidly to the regulating wheel unit 15, the regulating wheel 18 thus being advanced or retarded, and the width of the grinding throat altered accordingly, in response to the longitudinal travel of the cam.

The cam responsive slide member 54 and its accompanying members will now be described in detail, particular reference being made to Figures 1, 2 and 3. A generally rectangular slide mounting block 55 is mounted and secured, e. g. by bolts 56, on the bed II so as to clear the slide member 14 at the rearward limit of its travel during normal operation of the grinder. A pair of elongated angular slide retaining members 57 are secured, as by bolts 58, to the top surface of the block 55 defining an inverted T-channel longitudinally parallel with the block for retaining therein a slide member 54 consisting of an elongated block-like member having an inverted Tshaped cross section. The upper surfaces of the ribs 59 extending laterally from the lower edges of the slide member 54 engage the lower surfaces of the overhanging portions of the slide retaining members 57.

The cam-responsive slide member 54 has an upstanding clamp 62 formed integral therewith, or secured thereto in convenient fashion, in which is clamped rigidly one end of a regulating wheel unit thrust rod 63. A thrust rod shoulder 61 is provided on the thrust rod 63 to bear against the forward side of the clamp 62 and a hub 60 is secured as by a set screw 41 to the outer end of the thrust rod, the shoulder 61 and hub 41 preventing slippage of the rod longitudinally in the clamp. Clamp screws 65 are provided for tightening the j aws of the clamp 6 2. The other end of the thrust 5 rod 63 is secured to the regulating wheel unit 15, preferably by way of an adjusting device,; such as a threaded adjusting sleeve 64, for adjusting the effective length of the rod, suitable hand spokes 40 being provided on the hub 60 for turning the 10 thrust rod 63 to effect the adjustment. It is apparent that other thrust rod securing and adjusts ing means can be employed, if desired; for securing the thrust rod 63 to the cam responsive slide 54 and for adjusting its length.

The upper surface 66 of the slide mounting block 55 in provided with a transverse cam channel· 67 in which the cam 49 travels, the depth of the channel being such that the lower and upper surf aces.of the cam maintain sliding contact with 20 the bottom of the channel and with the bottom of the cam responsive slide member 54, respectively. A series of cam guiding rollers or idlers 68 are positioned and aligned in the cam channel 67 and mounted on pins 70 set in the bottom, of the cam 25 channel in such fashion that the planar cam guide surface 51 bears on the peripheries thereof to. pre? vent lateral sliding motion of the cam 49 in a rearward direction,.!...e. in. a direction, away from the regulating wheel unit 15. The transverse cam 30 channel is, of course, sufficiently wide, to accommodate the cam.guiding rollers 68 and. the widest portion of the.; cam.

Forward of the cam and adapted to bear against the cam surface 53 thereof there is located a cam 35 follower consisting of a cam follower roller 69 mounted on a cam follower shaft 72 secured as by a set screw 71 in a. vertical bore 73 in the forward portion of the cam responsive slide member

54. The cam follower roller 69 is. located mainly 40 forward of the transverse cam channel 67 in a cam follower channel 74 in the upper surface of the slide mounting block 55 intersecting the cam channel 67 and shaped to permit lateral travel therein of the cam follower roller 69 in. a ₄₅ direction , parallel with the longitudinal axis, of the thrust shaft 63. Inasmuch as the cam follower roller 69 preferably has a face wider than the cam face 53, the cam follower channel 74 is, in such case, deeper than the cam channel 67 and 50 a shallow channel. 75 is formed in the. lower surface of the cam responsive slide member 54 in register with the cam follower channel 74.

It is apparent that the cam 49 will, during its travel in one direction, forward the regulating 55 wheel toward the grinding wheel and decrease the width of the grinding, throat but that during, its travel in the reverse direction it 'will not. return the regulating wheel to its original position. To accomplish this latter effect and to maintain the 00 cam follower roller S9 at all times in pressure contact with the cam surface 53 and the width of the throat at all times controlled by the cam, the slide mounting block 55 is bored longitudinally below the cam follower channel 74 to accommo_G5 date a regulating wheel unit return shaft 7 6 which is secured at its forward end, as by threads and a lock nut 30, to the sliding bed member 14. The return shaft bore 77 accommodating the return shaft 76 terminates at its rearward end in a larger 70 hydraulic return power cylinder 78, conveniently formed in a cylinder block 79 which is secured to the slide mounting block 55 as by bolts 82.

A piston 84, having a suitable channel and ring 85 around its periphery to prevent leakage of hydraulic fluid past it is slidably positioned in

2.878.346 the cylinder 78 and secured, as by a piston securing nut 86, to the end of the return shaft 76. Hydraulic fluid is admitted under substantially constant pressure into the cylinder 78 on the forward side of the piston 84 by way of a suitable fluid port 87 and a hydraulic fluid conduit 88 hereinafter more fully described. Due to the constant pressure of the fluid in the cylinder 78 on the forward side of the piston 84, the cam follower roller 69 will at all times be in pressure engagement with the cam surface 53 and the width of the grinding throat will at all times be controlled precisely by the contour of the cam surface 53. When the regulating wheel unit 15 is advanced in response to the urging of the cam surface 53 on the cam follower roller 69, hydraulic fluid is forced from the cylinder 78 through a suitable relief valve, as hereinafter explained, due to the forward movement of the piston 84. It is understood that after preliminary adjustment of the apparatus the sliding bed member 14 is locked to the regulating wheel unit 15, the two advancing and retreating as a unit. An additional advantage of the arrangement of parts shown is that because of the continuous pressure of the fluid in the return power cylinder 78 which opposes the pressure of the cam surface 53 on the cam follower roller 69, the adjusting means 64 for adjusting the length of the regulating wheel unit thrust rod 63 is always under compression. This compensates for any looseness or wear in the adjusting means and contributes to a high degree of accuracy in the synchronization of the travel of the regulating wheel unit IS and the work piece without the use of highly accurate and costly parts in the adjusting means and eliminates the necessity for their renewal upon the slightest amount of wear as would otherwise be the case.

An elongated work piece support 89 of Figure 1, is provided, conveniently in the form of an elongated trough, in which the work piece 92 is placed and along which it slides into the grinding throat to engage the grinding and regulating wheels 13 and 18, respectively. The work piece support 89 is secured at its end nearest the grinding throat, e. g. by welding, to a support plate 93 secured to the sliding bed member 14 as by bolts 90, or to a work holding fixture to which the blade 19 can also be secured, and is otherwise unsupported throughout its length. It thus advances and retreats with the slide member 14 and the regulating wheel 18 thus assisting somewhat in keeping the work piece 92 at all times aligned properly with respect to the grinding throat. It should be pointed out, however, that the alignment of the piece is effected principally by the grinding and regulating wheels themselves and that the machine will operate satisfactorily using a stationary flat table as the work piece support if means are provided to guide the work follower pivot 96, hereinafter referred to, in the same longitudinal path as the work piece itself.

As indicated previously, a work follower is provided which follows the work piece 92 closely as it is drawn through the throat in response to a feed component of the regulating wheel. The work follower in the modification shown comprises a work follower rod 94 positioned in the work support trough 89 substantially coaxial with a work piece 92 therein. The rod 94 is secured at its outer end, i. e. at its end farthest removed from the grinding throat, to a work follower block 95 which is conveniently contoured to slide easily along the work support 89 without danger of becoming disengaged therefrom, A work follower pivot 96 is mounted, preferably rotatably, on the top of the work follower block 95, the function of which will be hereinafter explained.

On the fulcrum supporting member 28 previously referred to there is positioned and secured a fulcrum bed block 97 longitudinally grooved in its upper surface to provide for the retention and sliding therein of a fulcrum block 98. The ful10 crum block 98 has rotatably mounted on its surface a fulcrum member 99 bored to receive slidably one end of an elongated work follower actuating lever 102. The actuating lever 102 has a circular hole intermediate its ends for receiving 15 the pivot pin 45 previously referred to and is prevented from becoming disengaged therefrom by a nut 101 threadably engaging the upper end of the pivot pin 45. The actuating lever 102 is provided at its end removed from the fulcrum 20 member 99 with an elongated follower pivot slot 103 to engage slidably the work follower pivot 96 to permit travel of the latter therein upon rotation of the actuating lever about its fulcrum so as to cause the work follower rod and block 25 94 and 95, respectively, to travel along the work piece support 89 in synchronism with the longitudinal travel of the cam 49. The parts are arranged so that the direction of travel of the pivot pin 45 is parallel with the direction of travel of 30 the work follower pivot 96 for reasons hereinafter explained.

The fulcrum block 98, upon which the rotatable fulcrum member 99 is mounted, is longtudinally adjustable in the channel of the fulcrum 35 bed block 97, suitable by a threaded fulcrum block adjusting rod 164 secured to the end thereof and extending through a hole in a fulcrum block adjusting plate 105 secured at the end of the channel in the fulcrum bed plate 97. A pair of 4u lock nuts 106, running on either side of the adjusting plate 105 on the adjusting rod 104, permits locking of the fulcrum block 98 at any position along the channel in the fulcrum bed block 97. It is apparent that, because the end portions 45 of the work follower actuating lever 192 engage the fulcrum member 99 and the work follower pivot 96, respectively, in slidable manner and because the pivot pin 45 and the work follower pivot 96 travel in parallel paths, the distance 50 traveled by the work follower rod 94 upon rotation of the work follower actuating lever 102 will at all times be in a constant ratio to the distance traveled by the pivot pin 45 for any particular setting of the fulcrum block adjusting rod 55 ^ίΜ·

It will be noted that, since the free end of the work piece follower rod 94 should, for best results, follow the work piece 92 at not more than a short distance so that the constancy of ₆₀ the distance can be judged accurately by the operator, and that since the grinding action on the work piece 92 continues until the piece has passed entirely through the throat, it would be essential that the diameter of the follower rod 65 94 be less than the diameter of the rear end of the work piece as it leaves the grinding throat to prevent grinding of the follower rod unless some other means for preventing this were provided. Since this frequently presents some diffi70 culty in the case of follower rods of small diameter in the way of keeping them straight and properly aligned it is sometimes advisable to provide means for arresting the travel of the work follower rod 94 before it has entered into the 75 grinding throat without at the same time ar2,575,346 resting or changing the rate of travel either of the work piece 92 through the throat or of the cam 49.

This is accomplished conveniently by providing a lever elevating arm ί 07 adjacent to and substantially .parallel with .the end of the work piece support 8 9 nearest the grinding throat which has a sloping upper «surface or ramp SC9 which engages the traveling lever as it approaches the throat and springs it .upward sufficiently to disengage it from the work follower pivot 96, but without interrupting the forward travel of the lever. After the lever has completed its forward travel, which stops short of its contact with either the grinding wheel or the control wheel, the direction of its travel is reversed, as hereinafter explained. As it slides down the inclined surface 109 the follower pivot slot 103 again engages the «work follower pivot 96. The lever elevating arm 107 is conveniently secured to a bracket 1(2 as by bolts i 13 or by welding, the bracket 112 being in turn secured .to the bed 11 as by bolts ί 14.

The hydraulic system for operating the cam 49, shown schematically in Figure 4, comprises an.hydraulic fluid reservoir ((5, a driving motor ill and a pump 1(6. for drawing fluid from the reservoir and delivering it under high pressure through a suitable high pressure conduit 118, the pressure therein being regulated to a convenient maximum value by a high pressure relief valve 119, any excess of fluid furnished by the pump returning to the reservoir by way of a suitable pressure control drain conduit 122.

The high pressure conduit 118 conducts fluid to a suitable distributor valve 125. A neutral return 35 conduit (27 conducts fluid from the distributor valve ( 26 back to the reservoir I! 5 when the operating handle (28 is in neutral position. Fluid from another outlet of the valve 126 is conducted, in response to proper manipulation of the handle (28, by way of a regulator valve conduit (29 to a fluid regulator valve (32 adapted to careful and accurate control of the rate of flow of fluid therethrough. From the regulator valve (32 the fluid flows by way of conduit 35, previously mentioned, to the hydraulic drive cylinder 34 to cause forwarding of the cam in a forward direction, i. e. during the grinding of the work piece. The speed of the forward motion of the cam 49 and of the wbrk follower rod 94 are regulated by means of 50 the fluid regulator valve (32 to cause the follower rod to follow the work piece at a substantially constant distance therefrom thus insuring synchronization of the travel of the work piece with the forward travel of the regulating wheel unit 15 and, accordingly, with the variation in width of the grinding throat.

Fluid from a third outlet of the distributor valve (26 is conducted, upon proper manipulation of the handle (28, by way of a cam return conduit 123 to a constant pressure inlet valve (24 and thence by way of a conduit 36, hereinbefore referred to, to the hydraulic drive cylinder 34 to cause retraction of the cam 49 and the work follower rod 94, it being apparent that the direction of travel of the cam and rod follower is determined by the position of the operating handle ί 28 which is manipulated manually. During the travel of the piston in the hydraulic cylinder 34 in the forward direction during the grindingstroke in response to the pressure of fluid entering the cylinder through the conduit 35, the fluid in front of the piston is vented by way of a pressure relief valve (25 and a conduit (30 to the sunply tank (15. When the piston in the cylinder 34 is forced in the opposite «direction due to pressure of fluid entering through the conduit 36, fluid is forced backward through the regulator valve (32 and the conduit 129 and is by-passed through a suitably provided channels in the distributor valve :(26 to the conduit (27 and thence to «the fluid reservoir (15. The fluid regulator valve (32 and the distributor valve 126 are usually mounted on the side of the bed member ((, as 10 illustrated in Figure 1, or in any other location convenient for the operator.

A portion of the fluid passing into the high pressure conduit if 8 flows by way of a constant pressure outlet valve 134 and thence by way of a 15 conduit 88, previously referred to, to the return power cylinder 78 to maintain pressure at all times therein. An additional pressure relief valve 135 is provided to relieve pressure in the conduit-88 and vent fluid from the cylinder 78 20 during the forward travel of the cam 49. Fluid vented through the relief valve 135 drains by way of a vent drain 136 into the reservoir (i 5. A suitable distributor valve drain (38 and a.suitable regulator valve drain (37 are also usually «pro25 vided to convey any «fluidleaking from the respective valves to the reservoir (15.

It is apparent that proper operation of the apparatus will depend upon a proper setting of the several constant pressure and pressure relief 30 valves. The relief valve 119 should be set to open at a pressure higher than that at which the constant pressure inlet valve 124 is set to open and the constant pressure outlet valve (34 should be set to maintain a substantially constant working pressure in the conduit 88 and the cylinder 78 somewhat less than that at which the valve (24 opens. The pressure relief valve 135 should be set to open at a convenient'pressure higher than that for which the constant pressure outlet ⁴⁰ valve 134 is set but lower than that for which the relief valve 119 is set. The pressure relief valve (25 should be set to open at a pressure somewhat lower than that at which the valve 119 ouensbut higher than that for which the valve (24 is set. 45 By such a setting of the respective valves, the possibility that the pressure of hydraulic fluid in the cylinder 78 will fall to an undesirably low value, especially during the retraction of the cam when fluid is entering the cylinder 34 by way of conduit 36, is avoided.

Although the apparatus of the invention is, as mentioned previously, of particular value in the tapering of relatively flexible and limber elongated articles, it is pointed out that it is equally 55 adaptable to the grinding of large or rigid articles as well. It should also be pointed out that, depending upon the contour of the cam surface of the cam used, the apparatus can be employed to impart a variety of contours to the work piece 60 including straight tapers, parabolic tapers, reversed parabolic tapers and combinations thereof including sections ground without a taner. It is also apparent that, although the invention has been described as operating to grind a tapered 65 article beginning at the larger end, the cam can be reversed and the work piece ground from the smeP er toward the larger end.

The manner of dressing +he grinding and regulating wheels and of adiusting the latter to secure 7° a desired feed component have not been described in detail as these operations anH adjustments will be fully apparent +o those familiar with the art. It should be particularly mentioned, however, that best results are obtained when grinding rel75 atively limber articles of small diameter by ad11 justing the height of the work rest blade so that the longitudinal axis of the work piece as it travels through the grinding throat is below a line connecting the centers of the grinding and regulating wheels. Thus, in the grinding of glass fiber reenforced fishing rod blanks, this distance is usually maintained at about one inch.