US2127748A

US2127748A - Valve grinding apparatus

Info

Publication number: US2127748A
Application number: US730574A
Authority: US
Inventors: Harry G Miller
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-06-14
Filing date: 1934-06-14
Publication date: 1938-08-23
Anticipated expiration: 1955-08-23

Description

Aug. 23, 1938.. H. G. MILLER v VALVE GRINDING APPARATUS I 5 Sheets-Sheet 1 Original Filed June 14, 1934 Aug. 23, 1938. H. G. MILLER 2,127,748

' VALVE GRINDING APPARATUS Original Filed June 14, 1954 3 Sheets-Sheet 2 'A 9 H. G. MILLER 2,127,748 VALVE GRINDING APPARATUS Original Filed June 14, 1934 5 SheetsSheet 3 Patented Aug. 23, 1938 UNITED STATES PATENT OFFIQE Application June 14, 1934, Serial No. 730,574

Renewed December 28, 1937 6 Claims.

My invention relates to grinding apparatus.

One of the objects of my invention is to provide an improved grinding apparatus by means of which both the roughing cut and the finishing cut may be made by the same grinding cutter.

,A further object is to provide an improved grinding apparatus for use with the valves of internal combustion engines by means of which the valve is centered on two spaced unworn portions of the valve stem.

In the poppet valve type of internal combustion engines, the valve stems operate in tubular valve stem guides. These valve stem guides become worn and that part of the valve stem itself which operates in the valve stem guide also becomes worn so that it is no longer truly coaxial with, and at right angles to, the seating surface of the valve.

In re-surfacing the valve, it has been customary to grip the valve stem in a chuck for the grinding operation. The chuck grips on a worn portion of the valve stem and furthermore'grips at one part only of the valve stem, as a result of which the finished ground surface of the valve is not ground coaxial with respect to the unworn portion of the valve stem and does not lie in a plane at right angles to the axis of the unworn portion of the valve stem. By the use of my improved apparatus, the valve stem, during the grinding operation, is gripped at two portions spaced a substantial distance apart, both of which portions are unworn portions of the valve stem. As a result of this, the surface ground on the valve is coaxial with the unworn portions of the valve stem and the seating surface of the valve is at right angles to the axis of the unworn portions of the valve stem.

In my co-pending application, Serial No. 709,686, filed February 5, 1934, I have disclosed apparatus for resurfacing the valve seat of an internal combustion engine in such a manner that the re-surfaced valve seat will be coaxial with the unworn portions of the valve stem guide and will lie in a plane at right angles with respect to this axis. By the use of the apparatus of the present application for re-surfacing the valves and the use of the apparatus of the aforesaid co pending application for l e-surfacing the valve seats, results are accomplished in the way of securing a more nearly perfect seating contact between the valve and seat than have been hitherto attainable. The seating is so nearly perfect that the blow torch action of the hot gases is eliminated, thus preventing scoring of the valves and seats by the rapid flow under pressure of the hot gases when the valve is in the closed position. It hasbeen found by tests that the temperature of the hot gases isincreased approximately 1100 by this blow torch action, due to faulty contact between valve and seat. The elimination of this blow torch action not only prevents scoring of the valves and seats but also materially lowers the temperature of the motor head.

In the drawings, in which my invention is illustrated- 10 Figure l is a plan view of my improved valve grinding apparatus;

Fig. 2,,is an elevational view, as seen from a lower side of Fig. 1

Fig. 3 is an elevational View as seen from the right of Fig. 1;

Fig. 4 is a vertical sectional view on the

line

4,4 of Fig. 1; 1

Fig. 5 is an axial sectional view on the line 5-5 of Fig. 1, showing the means for centering the valve in the grinding operation;

Fig. 6 is a section on the line 6-6 of Fig. 5; and

Fig. 7 is a schematic sectional view showing a different form of grinding cutter and valve.

In a general way, the construction shown in the drawings comprises agrinding cutter l, having a cylindrical face portion 2 dressed to provide a roughing cut on the valve or other work and a slightly tapering or conical portion 3 for providing a smooth finishing cut on the work, an electric motor 4, on the shaft 5 of which the grinding cutter I is secured, means shown in detail in Fig. 5 for engaging and centering the valve stem on both sides of that portion of the stem which engages the valve stem guide whereby the stem is centered by two spaced unworn portions of the valve stem, and means whereby the rotatable support or holder 6 for the work may be swung either to move the cutter-engaging portion of the work along a generatrix of the cylindrical roughing portion of the grinding cutter or along ageneratrix of the conical finishing portion of the grinding cutter, and screw feed means "i for feeding the work support toward the axis of the grinding cutter I.

In order to enable the rotatable support for the valve stem to be shifted from a position. in which the valve cooperates with the roughing portion of the cutter to a position in which it cooperates with the finishing portion of the cutter, the support or bracket 8 on which the rotatable work holder 6 is itself in turn mounted to swing on a horizontal pivot pin 9 (Fig. 4) carried by a support or table [0 which in turn can be swung about a vertical pivot pin H, the axis of which is substantially tangential to the cutter l at its portion of grinding contact with the work l2.

As indicated above, the rotatable work holder 6 has two swinging movements,-one a swinging movement with the table II] about a vertical axis on the pivot pin ll (Fig. 4) for shifting the work holder 6 from a position in which it cooperates with the roughing portion 2 of the cutter to a position in which it cooperates with the finishing portion 3 of the cutter, and the other a limited swinging movement with the bracket 8 about a horizontal axis with the pin 9 (Fig. 4) to shift the seating portion l3 of the valve across the roughing portion 2 of the cutter in one position of adjustment about the vertical axis and to shift the seating portion of the valve across the finishing portion 3 of the cutter in the other position of adjustment about the vertical axis. As indicated above, the vertical axis is substantially tangential to the cutter at its portion of grinding contact with the work. In one position of adjustment about its vertical axis the swinging movement of the work carrier 6 about its horizontal axis will cause the cutter-engaging portion of the valve to move along a straight-line generatrix of the roughing portion 2 of the cutter and in the other position of adjustment about its vertical axis the swinging movement of the work carrier 6 about its horizontal axis will cause the cutter-engaging portion l3 of the valve to move along a straight-line generatrix of the finishing portion 3 of the cutter.

The swinging movement of the bracket about its horizontal axis is limited by the engagement of the semi-cylindrical extension I4 of the swinging bracket 8 with the abutments IS on the swinging table 10.

The swinging movement of the bracket-carrying table Ill is effected by means of a circular cam l6 (Figs. 1, 2, and 4) having an "operating handle I! and pivotally mounted in the table at la. The swinging movement of the bracketcarrying table is limited by the engagement of the operating handle I! with the ends IQ of the slot in the table, in which slot the handle operates. The swinging table is held in either of the extreme positions to which it may be adjusted by means of a link 20 pivotally connected with the cam l6 and slidable in a pivot pin 2| and a coil compression spring 22, one end of which engages a shoulder on the swinging link 20 and the other end of which engages the pivot pin 2|.

The feeding movement of the work toward the cutter is effected by moving axially the aforesaid pivot pin 9, on which the work-carrying bracket 8 is mounted, by means of a feed screw I. This feed screw is threaded in a nut 23 carried by the table It]. The end of this screw 1 has a pocket in which a ball 24 is seated, which ball engages the end of the slidable and rockable pin 9 on which the swinging bracket 8 is mounted, whereby an anti-friction bearing is provided between the feed screw and the slidable rockable pivot pin. The pivot pin is held in cooperative relation with respect to the feed screw by means of a coil compression spring 25.

Before describing in detail the rotatable work holder, I will describe in a general way the use of the apparatus for effecting both the roughing and finishing cut on the same cutter.

For the roughing cut, the table-swinging handle I1 is moved to the position shown in Fig. 1, in which position the horizontal axis, at 9, of the swinging work-carrying bracket 8 lies in a vertical plane substantially perpendicular to that straight-line generatrix of the roughing surface 2 which is in contact with the work to be operated on. In this position therefore the swinging movement of the work holder carrying bracket about its horizontal axis, at 9, will move the cutter-engaging portion of the work along a straight-line generatrix of the roughing portion 2 of the cutter. Suitable transmission is provided between the motor 4 and the rotatable work holder 6 for rotating the work in a direction such that the contacting portions of the work and cutter will move in opposite directions. When the motor is put in operation, both the cutter I and the work 12 are rotated and the swinging work holder carrying bracket 8 is swung back and forth to move the seating portion I3 of the valve across the roughing portion 2 of the cutter. The work may be fed toward the cutter by means of the feed screw 1 until the desired depth of out has been taken.

After the roughing out has been taken, the table-shifting lever H (as seen in Fig. 1) is moved to the left, until the bracket-carrying table 10 has been moved to its other extreme position. In this other position. the horizontal pivot pin 9 has been moved to a position in which its axis lies substantially in a vertical plane perpendicular to that straight-line generatrix of the conical finishing surface 3 which is in contact with the work l2. In this position, therefore, the swinging movement of the work holder carrying bracket 8 with the horizontal rockable pivot pin 9 will move the cutter-engaging portion of the work along that generatrix of the conical finishing surface 3 of the cutter which is in engagement with the work. The roughing and finishing surfaces of the cutter are of course suitably dressed to effect the desired cutting operation.

A dressing tool may be mounted on the swinging bracket 8 so that the grinding cutter may be dressed simply by swinging the bracket 8 about the axis of its pivot pin 9. The shank of the dressing tool may be held in a socket portion 26 of the bracket by means of a set screw 21 operated by a hand lever 28 (Fig.

The aforesaid transmission, from the motor to the rotatable work holder comprises a small belt pulley 29 on the motor shaft 5, a belt 30 driven by this small pulley 29, a larger belt pulley 3| over which this belt runs, a small pulley 32 rotatable with this larger pulley 3|, a belt 33 driven from this small pulley, a larger pulley 34 driven from this belt, a shaft 35 on which this large pulley 34 is mounted, a small pulley 36 also mounted on this shaft, a belt 31 driven from this small pulley, and a large pulley 38 driven by this belt and rotatable with the rotatable work holder.

The rotatable work-holding construction, which is so important in securing the concentric grinding of the valve, is shown in detail in Figs. 5 and 6. As shown therein, a spring collet 39 is provided having spring fingers 4B which are forced into engagement with an unworn portion of the valve stem, which lies outside of the valve stem guide, and a rotatable valve stem holder 4| is provided in which the unworn end portion of the valve stem is snugly seated so that the valve stem 42 is thus held by two unworn portions which are spaced a substantial distance apart. This insures that the seating portion of the valve will be ground concentric with respect to the axis of the valve stem and in a plane perpendicular to this axis.

The tail stock 43 is adjustable toward and from the rotatable work-holding collet 39 by means of a guideway 44 on the swinging bracket 8, in which guideway the tail stock is slidably mounted. The tail stock is held in the desired adjusted position by means of a clamping screw 45 which extends through a slot 46 in the swinging bracket 8 and is threaded into the tail stock. The valve stem holder 4| is rotatable in a sleeve or pocket 41. A suitable anti-friction thrust bearing 48 is provided between the valve stem holder 4| and the bushing 41. The valve stem holder 4| is held against substantial endwise movement in the bushing by means of a screw 49 threaded through the sleeve 41 and engaging an annular groove 50 in the valve stem holder. This screw 49 also serves to hold the sleeve 41 against rotation by the engagement of its upper end in a slot in the bushing 52. A coil compression spring 53 serves to press the sleeve 41 and the valve stem holder 4| over toward the valve stem 42. The bushing 52 may be held in the tail stock by any suitable means, such as a bayonet joint connection.

The spring fingers 40 of the collet are forced into engaging relation with respect to the valve stem 42 by means of a conical surface 54 on the work holder 6 engageable with the inclined portions 55 on the collet fingers. When the collet is moved to the left, the collet fingers are forced into engagement with the valve stem. For effecting this gripping action, a plurality of rocking cam members 56 are provided which may be operated to spread apart the surfaces with which they engage by means of a slidable sleeve 51 cooperating with the operating fingers 58 of the rocking cams. One of the surfaces engageable by these cam members is an annular surface on the end of the work holder 6 which controls the collet fingers and the other is an annular surface on an adjustable collar 59 carried by the collet itself.

When the cam-controlling sleeve is moved to the position shown in Fig. 5, the cams are moved to spreading position and the collet is moved to the left to cause the collet fingers to grip the valve stem. When the collet is moved to the right from the position shown in Fig. 5, the cam fingers are released because of the flaring conical surface 54 of the work holder 6 so that the cams 56 no longer hold the surfaces engaged thereby in their spread position. This allows the collet fingers 40 to be freed from gripping engagement with the valve stem and allows the valve to be removed.

It will be noted that the opening at the left hand of the collet is materially larger in diameter than the diameter of the adjacent portion of the valve stem, so that the valve stem is centered solely by engagement of the collet fingers at one end of the valve stem and the engagement of the valve stem holder 4| at the other end of the valve stem.

The cam-controlling sleeve is operated by means of a hand lever 60 (Fig. 6) secured to a rock pin 6| on which rock arms 62 are mounted having shifter shoes 63 engageable in the annular groove 64 of the cam-controlling sleeve or collar 51.

The driven pulley 33 is secured to the rotatable work holder 6 so that the rotation of this pulley causes the rotation of the work holder 6 and hence of the collet carried thereby. The work holder 6 is rotatably mounted in bushings 65 in the bearing bracket. A suitable dust guard 66 may be provided for the end of the rotatable work holder.

The tail stock 43 may be adjusted for different lengths of valve stems by means of a clamping screw 45.

The construction of Fig. 7 is substantially the same as that just described except that here the work to be operated on is a valve 6'! having a fiat face 68 which is mounted on a bracket similar to the bracket 8, which bracket in turn is mounted on a swinging table similar to the table ID in such a manner that the fiat face 68 of the valve may be made to cooperate either with the beveled portion 69 of the grinding cutter or with the flat portion thereof. In this form the swinging movement of thetable isabout a vertical axis through the point H which is the point of contact of the valve seat 68 with the common diameter of the grinding surfaces Ill and 69. This vertical axis is the axis of the pivot pin II of the swinging table H]. The axis of the horizontal pivot pin 9 in this construction may be swung from the position indicated at A-B in Fig. '7, in which the beveled grinding surface 69 cooperates with the work, to the position indicated at C-D, in which the flat portion 10 of the grinding cutter cooperates with the valve seat 68.

It will be seen that by the use of the above apparatus both the roughing cut and the finishing cut may be made by the same grinding cutter, thus cutting down the time required for the complete operation. I It will also be seen that by the use of the above construction, the valve is centered on two spaces, unworn portions of the valve stem, whereby the surface ground on the valve is coaxial with the unworn portion of the valve stem and the'general plane of the seating surface of the valve is at right angles to the axis of the unworn portions of the valve stem.

Further modifications will be apparent to those skilled in the art and it is desired, therefore, that my invention be limited only by the prior art and the scope of the appended claims.

Having thus described, my invention, what I claim and desire to secure by Letters Patent is:

1. A grinding apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface having a surface of revolution generated by a substantially straight line generatrix, means for rotatably supporting the work, and means whereby the work support may be guided either to move the wheelengaging portion of the work along a generatrix of one of said grinding surfaces or to move the wheel-engaging portion of the work along a generatrix of the othergrinding surface, said guide means comprising means for mounting the work support to swing about an axis substantially tangential to the cutter atits portion of grinding contact with the work for shifting the work from one grinding surface to the other, and means for mounting the work support to swing about a second. axis which is shiftable about said first axis, said second axis in one position being substantially perpendicular to a plane through said first axis and a generatrix of one of said grinding surfaces, and in another position being substantially perpendicular to a plane through said first axis and a generatrix of said other grinding surface.

2. A grinding apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface having a surface of revolution generated by a substantially straight line generatrix, means for rotatably supporting the work, means whereby the work support may be guided either to move the wheel-engaging portion of the work along a generatrix of one of said grinding surfaces or to move the same wheel-engaging portion of the work along a generatrix of the other grinding surface, said guide means comprising means for mounting the work support to swing about an axis substantially tangential to the cutter at its portion of grinding contact with the work for shifting the work from one grinding surface to the other, means for mounting the work support to swing about a second axis which is shiftable about said first axis, said second axis in one position being substantially perpendicular to a plane through said first axis and a generatrix of one of said grinding surfaces, and in another position being substantially perpendicular to a plane through said first axis and a 'generatrix of said other grinding surface, and means for feeding said work support to move the work toward the cutter.

3. A grinding apparatus for effecting a roughing cut and a finishing cut on a work surface of revolution generated by a straight-line generatrix, said apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface being a surface of revolution generated by a substantially straight-line generatrix, said surfaces having one common diameter, rotatable work-supporting means coaxial with said work surface, means for changing the angle of the axis of the rotatable worksupporting means with respect to the axis of the rotatable grinding means from a position in which there is rectilinear engagement be tween one of said coaxial grinding surfaces and the work surface to a position in which there is rectilinear engagement between the other of said coaxial grinding surfaces and the same work surface, and guide means for controlling relative movement between said rotatable work support and rotatable grinding means in each of said two positions to effect a relative shifting between the engaging rectilinear elements of the work surface and grinding means in the direction of the line of rectilinear engagement.

4. A grinding apparatus for effecting a roughing cut and a finishing cut on a work surface of revolution generated by a straight-line generatrix, said apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface being a surface of revolution generated by a substantially straight-line generatrix, rotatable work-supporting means coaxial with said work surface, means for changing the angle of the axis of the rotatable work-supporting means with respect to the axis of the rotatable grinding means from a position in which there is rectilinear engagement between one of said coaxial grinding surfaces and the work surface to a position in which there is rectilinear engagement between the other of said coaxial grinding surfaces and the same work surface, and guide means for controlling relative movement between said rotatable work support and rotatable grinding means in each of said two positions to effect a relative shifting between the engaging rectilinear elements of the work surface and grinding means in the direction of the line of rectilinear engagement, said angle changing means comprising means for effecting relative pivotal angular adjustment between the work support and the grinding means about an axis substantially tangential to the grinding surface at its portion of engagement with the work.

5. A grinding apparatus for effecting a roughing cut and a finishing cut on a work surface of revolution generated by a straight-line generatrix, said apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface being a surface of revolution generated by a substantially straight-line generatrix rotatable work-supporting means coaxial with said work surface, means for changing the angle of the axis of the rotatable work-supporting means with respect to the axis of the rotatable grinding means from a position in which there is rectilinear engagement between one of said coaxial grinding surfaces and the work surface to a position in which there is rectilinear engagement between the other of said coaxial grinding surfaces and the same work surface, and guide means for controlling relative movement between said rotatable work support and rotatable grinding means in each of said two positions to effect a relative shifting between the engaging rectilinear elements of the work surface and grinding means in the direction of the line of rectilinear engagement, said guide means comprising means for effecting relative pivotal angular adjustment between the work support and the grinding surface about an axis perpendicular to a plane tangential to the operating grinding surface and containing the line of rectilinear engagement between the grinding surface and work surface.

6. A grinding apparatus for effecting a roughing cut and a finishing cut on a work surface of revolution generated by a straight-line generatrix, said apparatus comprising rotatable grinding means having two coaxial grinding surfaces, each grinding surface being a surface of revolution generated by a substantially straight-line generatrix, rotatable work-supporting means coaxial with said work surface, means for changing the angle of the axis of the rotatable work-supporting means with respect to the axis of the rotatable grinding means from a position in which there is rectilinear engagement between one of said coaxial grinding surfaces and the work surface to a position in which there is rectilinear engagement between the other of said coaxial grinding surfaces and the same work surface, and guide means for controlling relative movement between said rotatable work support and rotatable grinding means in each of said two positions to effect a relative shifting between the engaging rectilinear elements of the work surface and grinding means in the direction of the line of rectilinear engagement, said angle changing means comprising means for effecting relative pivotal angular adjustment between the work support and the grinding means about an axis substantially tangential to the grinding surface at its portion of engagement with the work, said guide means comprising means for effecting relative pivotal angular adjustment between the work support and the grinding surface about an axis perpendicular to a plane tangential to the operating grinding surface and containing the line of rectilinear engagement between the grinding surface and Work surface.

HARRY G. MILLER.