US2988966A - Method and apparatus for surface conditioning ingots and the like - Google Patents

Description

June 20, 1961 B. SPENCER D. METHOD AND APPARATUS FOR SURFACE CONDITIONING INGOTS AND THE LIKE Filed Feb. 5, 1958 5 Sheets-Sheet 1 I E l I l 51 I I] as BI 75 I 1 INVENTOR.

DONALD B. SPENCER ATTORNEYS June 20, 1961 METHOD AND APPARA INGOTS AND THE LIKE Filed Feb. 3, 1958 D B. SPENCER TUS FOR SURFACE CONDITIONING 5 Sheets-Sheet 2 ZIA' INVENTOR.

o DONALD B. SPENCER 7 ATTORNEYS June 20, 1961 D. B. SPENC 2,988,966

' METHOD AND APPARATUS FOR SUR CE CONDITIONING INGOTS AND THE LIKE Filed Feb. 3, 1958 5 Sheets-Sheet 3 t no INVENTOR.

DONALD B. SPENCER ZMZW/XMW ATTORNEYS June 20, 1961 D. B. SPENCER 2,988,966

METHOD AND APPARATUS FOR SURFACE CONDITIONING INGOTS AND THE LIKE 5 Sheets-Sheet 4 Filed Feb. 5, 1958 IHIHIH H! HNIIHHIH 1 l l I 1 INVENTOR.

DONALD B. SPENCER ATTORNEYS June 20, 1961 D. B. SPENCER METHOD AND APPARATUS FOR SURFACE CONDITIONING INGOTS AND THE LIKE 5 Sheets-Sheet 5 Filed Feb. 3, 1958 INVENTOR.

ATTORNEYS United Stat t? 2,988,966 METHOD AND APPARATUS FOR SURFAC'E CON- DITIONING INGOTS AND THE LIKE Donald B. Spencer, Portland, Oreg., assignor to Guy F.

Atkinson Company, South San Francisco, Calif., a corporation of Nevada Filed Feb. 3, 1958, .Ser. No. 713,018

19 Claims. (Cl. 90-34) This invention relates to an improved method and machine for removing surface imperfections in air or vacuum cast metal ingots and billets and other heavy work pieces. The class of work to which the invention chiefly pertains is generally known as ingot scalping and billet surface conditioning.

It has heretofore been the practice to remove such surface imperfections on a, lathe or by grinding. A lathe operation, however, is relatively slow and costly, and does not provide the desired rigidity of support necessary for a more rapid surface conditioning operation nor do available tools provide satisfactory life when cutting the surface skin, particularly on ingots of refractory metals. Grinding also is slow and costly and for certain refractory metals is not satisfactory or economical. The surface imperfections'referred to consist of discontinuities and non-homogeneous structure, roughness, variations in hardness and sometimes impurities commonly extending to a depth of one-sixteenth to one-half inch. Because of the manner in which the work piece is supported and rotated, and the eccentric tool loading, a cut of such depth must be made at a feed of .010 inch maximum 011 a lathe and at very low surface speeds. It is, therefore, usually necessary to make a series of cuts in order to remove sufiicient depth of materialto eliminate all imperfections from the outside of the ingots or billets. Furthermore,only cylindrical work can be machined in a lathe whereby no satis factory and eflicient machinery exists other than grinders or planers for the surface conditioning of square, rectangular or octagonal billets, which shapes are often advantageous for subsequent operations such as rolling or forging. 7

It is, therefore, the general object of the present'invention to provide an improved method and apparatus for machining heavy workpieces.

Another object is to provide an improved machine for removing surface imperfections in ingots and billets, particularly ingots and billets of the refractory metals and super alloys.

Another object is to provide an improved machine capable of removing large amounts of metal under conditions of extremely low surface cutting speeds, low tool and work piece temperatures, and without the use of coolants.

Another object is to provide a surface conditioning method and apparatus which will operate on square, rectangular or octagonal shapes, as well as round.

Another object is to provide hydraulic clamping means for positioning a heavy work piece.

Another object is to provide an extremely rigid support for a work piece having a feed movement.

Another object is to provide an improved feed movement which is not subject to variation by torsional or bending deflections in the machine.

Patented June 20, 1961 Another object is to provide a machine of the type described which feeds the work piece in rectilinear motion with respect to stationary cutting tools.

Another object is to provide a vertical feed movement for heavy work pieces in a machining operation.

Another object is to provide a surface conditioning machine having a plurality of cutting tools arranged to make a plurality of cuts simultaneously on a work piece. 7

Another object is to provide a surface conditioning machine having a plurality of cutting tools operable simultaneously on. all sides of a work piece to balance the tool loading and minimize deflection in the machine.

Another object is to provide a surface conditioning machine for ingots and billets which will operate to the full depth of material to be removed in a single cut in the majority of cases.

Another object is to provide a machine which will support a work piece with all its longitudinal surfaces available for cutting so that all sides may be finished without relocating the work piece in its supporting means.

Another object is to provide a machine for the purpose described wherein the loading from the weight of the work piece and tool pressure is not imposed upon metal bearings as in the case of a lathe.

Another object is to provide a liquid supporting medium for heavy work pieces in a machining operation.

While the present machine is especially designed for removing surface imperfections from ingots and billets, it is to be understood that the principles of the invention may be applied to other machining operations where similar problems arise. The invention is, therefore, notto be limited to use on ingots and billets, as the features of the present construction may be utilized to advantage in the machining of still other types of work pieces.

, In the practice of the present invention, the ingot or billet is chucked and clamped between two opposed pistons or rams which are movable by the action of hydraulic pressure in a pair of cylinders to provide a rectilinear working stroke. In the illustrated embodiments, the work piece is stroked vertically between upper and lower vertical cylinders but the cylinders may be disposed horizontally to impart a horizontal stroke if desired. In the illustrated embodiments, the weight of the work piece is supported on the lower piston whereby the machine is without bearings or frame members subject to loading and deflection in the conventional manner. While one piston is advanced in feed movement by hydraulic pressure, the movement of the other piston is subject to hydraulic restraint suflicient to hold the work piece rigidly between the two pistons.

A plurality of cutting tools are mounted in symmetrical arrangement around the piston axis to engage the work piece simultaneously on opposite or all sides thereof. In

' this manner the tool loading on the work piece is essentially balanced, whereby the usual deflection produced by a single tool is eliminated. Thus, the major forces which give rise to objectionable deflection in conventional equipment are balanced or neutralized so that cuts can from the following specification and drawings which describe and illustrate two embodiments of machine for carrying out the method of the invention. It is to be understood, however, that the invention may take other forms and certain features may be used without others as various changes in the construction and arrangement of parts will occur to persons skilled in the art. All such modifications within the scope of the appended claims are included in the invention.

In the drawings:

FIGURE 1 is a side elevation view of a first embodiment of the invention, certain parts being'shown in section;

FIGURE 2 is a sectional view in reduced scale of the machine shown in FIGURE 1', taken on the line 2-2 of FIGURE FIGURE 3 is a side elevation view at right angles to FIGURES 1 and 2;

' FIGURE 4 is a cross sectional view taken on the line 4-4 inFIGURE 1;

' FIGURE 5 is a cross sectional view taken on the line 55 in FIGURE 1;

FIGURE 6 is a sectional view of a tool holder taken on theline' 6'6 of FIGURE 5;

FIGURE 7 is a sectional view of a tool holder taken on the line 77 of FIGURE 5;

FIGURES 8-11 are diagrams showing positions of the pistons and work piece in successive stages of operation;

FIGURE 12 is a plan view of a work piece after a number of cuts have been made;

FIGURE 13 is a fragmentary sectional view of a modification having a rotary tool holder block;

FIGURE 14 is a fragmentary bottom plan view of the tool holder block shown in FIGURE 13;

FIGURE 15 is an enlarged view of certain details of FIGURE 13 showing a tool holder in cutting position; and

FIGURE 16 is a view similar to FIGURE 15 showing the tool holder pivoted to non-cutting position.

Embodiment in FIGURES 1 to 7 Y The machine illustrated in the drawings comprises a pair of heavy and rigid upright frame members 10, preferably securely fastened by suitable anchor bolts to a concrete foundation 11 on opposite sides of a well 12. Projecting downwardly into the well 12 is a cylinder 13 equipped at its upper end with a liner 14 and suitable sealing means to slidably receive a cylindrical lower piston or ram, 20. On the upper end of cylinder 13 is an integral rectangular supporting frame 21 bolted or otherwise se-' cured to the upright machine frames 10. Frame 21 has horizontal flanges 21A engaging in grooves in the frame members to form a positive interlock between the parts. The lower end of the cylinder is connected with a pipe for the admission and relief of hydraulic fluid.

The upper end of ram projects out of cylinder 13 and is connected with a worm gear 22 which may be turned by a worm 23 to rotate the ram in the cylinder. Worm 23 is fixedly mounted on a shaft 24 having suitable operating means such as hand wheel 25. Worm shaft 24 is mounted for rotation in bearing brackets 26 on a rectangular guide plate 27 which slides up and down with the ram in vertical guides 28 on the upright frame members 10, as shown in FIGURE 4. In the lowermost position of guide plate 27 its feet 27A rest on a flat top surface of frame 21. The ram and worm gear 22 rotate relative to plate 27 when worm 23 is turned, whereby, when the worm is set in adjusted position, the ram cannot rotate. A chip collecting pan 29 rests on guide plate 27.

Mounted on the upper end of ram 20 is a hardened steel holding shoe 30 having upwardly projecting teeth in its top surface to engage and support the ingot or billet A. A vertical bore in the center of shoe 30 contains a center point 31 which is pressed upwardly above the supporting surface of the shoe by a spring 32 in the bore. This center point is used for locating a central depression formed in the bottom end of the ingot in the center of the shoe 30' which, by reason of its central bore, is annular in shape and concentric with the vertical axis of ram 20. Thus, the center point 30 is precisely on the ram axis and an ingot having a bottom depression in the geometrical center of a square cut bottom surface will be in balance on the supporting shoe.

Bolted or otherwise secured to the upper ends of upright frame members 10 is a central frame structure 35 carrying on its lower end a tool holder block 36. Frame 35 has horizontal flanges 35A engaging in grooves in the frame members 10 to form a positive interlock between the parts. On the uper frame 35' is mounted an upper vertical cylinder 37 which in the present embodiment is of less diameter than the lower ram 20. Upper cylinder 37 is equipped with a piston 38 carrying a cylindrical ram 40 of smaller diameter than the piston. The lower side portion of ram 40 is equipped with a suitable guide member 41 slidable in guide means in a central opening in tool holder block 36 and a central vertical opening 42 in frame 35 to provide lateral rigidity for the lower end of ram 40. Guide member 41 in the present instance is circular, whereby the ram 40 and piston 38 may rotate.

The lower end of ram 40 is equipped with a hardened steel holding shoe 43 having a projecting center point 44 similar to the lower center point 31. Center point 44 is used to locate a conical recess in the geometrical center of the top end surface of the ingot on the axis of ram 40 and cylinder 37 which is in alignment with the axis of lower ram 20 and cylinder 13. Opening 42 and the central opening in the tool holder block 36 are of suflicient size to admit a work piece A slightly larger than ram 40.

Shoes 30 and 43 are smaller in diameter than the work piece so as not to engage the cutting tools presently to be described when the ends of the work piece travel beyond the cutting tools at the end of each stroke.

The upper end of cylinder 37 is connected with a pipe 45 for hydraulic fluid and the lower end is connected with a similar pipe 46. Just below the connection with pipe 46 is a ring seal 47 around the ram 40. By reason of the fact that ram 40 is of smaller diameter than piston 38, hydraulic fluid introduced through pipe 46 will raise the piston and ram.

- Referring now to FIGURES 5, 6, and 7, the tool holder block 36 is equipped on its under side with guideways 48 for a plurality of tool holders 49. For machining a cylindrical work piece, the guideways 48 are directed radially toward the common ram axis, and each tool holder49 carries a radially directed cutting tool 50. The tool is held in adjusted position in the tool holder by means of adjusting screw 51 and clamp screws 52.

Each tool holder 49 is equipped with a cross slot 53 engaged by an eccentric head 54 on a stub shaft 55 journaled in block 36. Each stub shaft 55 carries a small spur gear 56. The four gears 56 associated with the four tool holders shown in FIGURE 5 may be rotated simultaneously by a ring gear 60 which is rotatable on a cylindrical bearing surface 61 in block 36 concentric with the ram axis. Ring gear 60 isrotated by a pinion 62 connected with a suitable operating device such as handle 63. Thus, by swinging the handle 63 in one direction, all the tools 50 may be simultaneously retracted to clear the work piece, and by swinging handle 63 in the opposite direction, the tools are advanced into position for a cut. Suitable stop means, not shown, are provided to place the tools in proper cutting position when handle 63 is swung to the limit of its movement. The tools 50 preferably have an adjustable cutting position as determined by adjusting screws 51 and are usually not advanced for successive cuts as in most conventional machines for this purpose. It is within the scope of the invention, however, to provide means whereby the operator can infeed all the tools simultaneously for a deeper cut it necessary. More than four tool holders may be provided, and, in any case, all the tools cut simultaneously in each working stroke of the work piece.

Hydraulic system The hydraulic system for stroking the work piece is illustrated schematically in FIGURE 2 for convenience of explanation. A first pump 70 withdraws hydraulic fluid from reservoir tank R to supply a pressure pipe 72. Pressure pipe 72 connects with a valve 74 on the pipe 15. Pipe 15 is also connected with a pressure gauge 75.

A second pump 71 withdraws hydraulic fluid from reservoir R to supply a pressure pipe 73. Pressure pipe 73 has a branch 76 connected with a valve 77 leading to the pipe 46. Another branch of pressure pipe 73 connects with a valve 78 connected with a pipe 79. Pipe 79 is in turn connected with a valve 80 leading to the pipe 45 which is equipped with a pressure gauge 81.

It is understood that both pumps are equipped with the usual by-pass valves (not shown) which may be adjusted to produce the same or different maximum working pressures in pressure pipes 72 and 73. The pumps are adapted to operate continuously to supply hydraulic fluid to said pipes as needed, the pumped fluid being by passed to the reservoir after the predetermined maximum pressures are established. r

A return pipe 85 is also connected with the reservoir tank R. Valve 74 in one position connects cylinder 13 with pressure pipe 72 and in a second position it connects the cylinder 13 directly with a branch return pipe 86. In a third position the valve 74 connects the cylinder with a pipe 87 which passes the discharge from cylinder 13 through an adjustable pressure relief valve 90 to the return pipe 85.

Another branch 91 of return pipe 85 is connected through a valve 92 with pipe 46. The valves 77 and 92 permit pipe 46 to be connected with either the pressure pipe 73 or return pipe 85.

Return pipe 85 is further connected with a pipe 93 leading to valve 80, and to an adjustable relief valve 95 connected through a pipe 96 to the pipe 79. Valve 80 thereby permits pipe 45 to the connected directly with return pipe 85 by Way of pipe 93 or to pipe 79. When valve 80 is turned to the position shown in FIGURE 2 connecting pipe 45 with pipe 79, the valve 78 may be opened to supply fluid to pipe 45 at a maximum pressure determined by the adjustment of relief valve 95. When valve 78 is closed it will be appreciated that relief valve 95 will maintain pressure in pipe 45 only when piston 38 is moving upward. The importance of this feature of selective control will be explained in connection with the operation of the machine.

When valve 80 is rotated a quarter turn counterclockwise, the source of pressure is cut off from pipe 45 and the flow from this pipe, if it is carrying discharge from cylinder 37, is shunted around pressure relief valve 95 to discharge the cylinder directly into return pipe 85 at approximately atmospheric pressure.

The schematic hydraulic diagram in FIGURE 2 shows the essential valve and piping connections in simplified form for convenient explanation of the operation of the system. In practice the manually operable valves are ganged together in two multiple valve units 98 and 99 for operation by a pair of-hand-les 100 as shown in FIGURE 1. It is also within the scope of the invention to provide power operating devices for such valve units responsive to the movements of the work piece, and other refinements, for automatic operation.

The difference in the diameters of ram 20 and piston 38 permits the use of a single pump hydraulic pressure system if desired. The same unit fluid pressure applied to both upper and lower cylinders produces a superior force on the lower ram to overcome tool resistance and the weight of the Work piece and move the work piece upward. There are also certain operational advantages in a single pressure system which may be utilized.

The present two pump system, however, has the. advantage of maintaining constant clamping force on the work piece regardless of tool resistance or piston velocity. It will be appreciated that with valve in the position shown in FIGURE 2 and valve 78 open during the upward working stroke, the clamping force on the work piece is determined solely by the adjustment of relief valve 95. This clamping force will not be reduced by excessive tool resistance even to the point of stopping the movement of the work piece.

Another important advantage of the two pump system is that it permits the use of upper and lower cylinders of equal diameter since the adjustment of pressure relief valve does not limit the maximum pressure available from pump 70 to drive the lower ram- 20. In large machinery the saving by making both cylinders the same size may more than oif-set the cost of the second pump.

In any case, the point to be emphasized is the inherent flexibility of the present machine in regard to the variables mentioned whereby various modifications within the scope of the invention may be utilized to the greatest advantage for the particular work to be done.

Operation The method of the invention and the operation of the machine and hydraulic system will now be described with reference to FIGURES 2 and 8-12. The ingot A will be used as an example of a work piece to be surface conditioned.

The ingot or billet is first prepared by cutting the ends 01f flat in planes perpendicular to its longitudinal axis. Then conical depressions are cut in the centers of the top and bottom surfaces to receive the center points 3 1 and 44.

Before the ingot A can be placed in the machine, the lower ram 20 must be retracted downward and the upper ram 40 must be retracted upward. This is accomplished by manipulation of the valves shown in FIGURE 2. Valve 74 is turned to the position shown, connecting pipe 15 with return branch pipe 86 whereupon ram 20 and work holding shoe 30 will drop by gravity to the lower position shown in FIGURES 2 and 8. Upper ram 40 is raised by closing valve '92 and opening valve 77 to admit pressure to the lower end of cylinder 37 under piston 38. Valve 80 is turned to connect pipe 45 with pipe 93 for free discharge from the upper end of the cylinder.

The ingot is then placed in position on lower work holding shoe 30 and held steady while the upper ram 40 is brought down, as shown in FIGURE 8, to engage center 92 and, at the same time, turning the valve 80 to the posi tion shown in FIGURE 2 to connect pipe 45 with pipe 79. Pressure is admitted to pipe 79 by opening valve 78. The ingot is thereby clamped between the work holding shoes 30 and 43.

The tools 50 are then projected to cutting position by lever 63.

To make the first cutting stroke, valve 74 is turned to connect the pipe 15 with pressure pipe 72 causing the lower ram 20 to move upward, as shown in FIGURE 9. Valve 77 is left closed and valve 92 is left open. Valve 78 is closed and valve 80 is left in the position shown in FIGURE 2 whereby fluid from the upper end of cylinder 37 is discharged through relief valve 95. The adjustment of this relief valve determines the clamping pressure on the ingot as long as the ingot is moving upward. This clamping pressure is not diminished by the tool resistance. It is evident, however, that, if the upward movement of substantially released.

When it is desired to maintain clamping pressure even.

stop, valve 78 may be left open to maintain the upper end of cylinder 37 in communication with the source of pressure in pipe 73. Fluid displaced from the upper end of cylinder 37 will then be discharged through relief valve 95 and, if valve 95 is adjusted to release at a pressure lower than that developed by pump 71, some fluid from the pressure pipe will also flow'back through valve 95. Constant clamping force is thereby maintained regardless of tool resistance and even if'the tool resistance should stop the upward movement of the ingot.

In FIGURE the ingot has almost completed its upward cutting stroke and is ready for its downward return stroke. When the lower edge of the ingot has cleared the tools 50, the latter are retracted by Swinging the handle 63 and the valves adjusted for return stroke.

' In order to maintain clamping pressure on the work piece during the down stroke, valve 74 is turned to conn'ect pipe with pipe 87 leading to relief valve 90. With valve 80 left in the position shown in FIGURE 2, valve 78 is opened, it it is not ready open, to introduce pressure to the upper end of cylinder 37 causing upper ram 40 to push the work piece and lower ram downward. The maximum pressure which can be established in the upper end of cylinder 37 on the down stroke is determined by the adjustment of relief valve 95 which was made for the up stroke, as above described. Relief valve 90, which functions only on the down stroke, is accordingly adjusted to open at a relatively low pressure to produce the desired clamping force on the down stroke, taking into consideration the pressure setting of valve 95 and the different piston areas in cylinders 13 and 37. Less clamping force is required on the return stroke than on the working stroke. Valve 92 remains open for free discharge from the lower end of cylinder 37. The return stroke just described is illustrated in FIGURE 11.

After the upper end of the ingot has dropped below the level of tools 50, the tools are returned to cutting position by means of lever 63 and the entire assembly of the two rains and ingot is rotated to a new cutting position by means of hand wheel 25. Clamping shoes 30 and 43 are of suflicient length to allow the over travel necessary for the ends of the ingot to clear the tools 50 in both directions of movement as above described since the sliding guides 27 and 41 are wider than the ingot and cannot themselves pass the tools 50.

The second upward stroke begins as soon as valve 74 is turned to connect pipe 15 with pressure pipe 72 by reason of the difference in end areas of ram and piston 33. On the second up-stroke valve 80 remains in the position shown in FIGURE 2 and valve 78 may be closed or left open as explained in connection with the first Working stroke.

In each working stroke the four tools 50 make four longitudinal cuts on opposite sides of the ingot to the full depth of the imperfections to be removed, as shown in FIGURE 12. The radial lines C C C and C indicate the tool center line positions relative to the ingot in four successive cutting strokes. It will be apparent that relatively few cutting strokes are necessary to remove the entire surface of the ingot. In scalping large ingots, a larger number of tools may be employed to advantage. A larger number of tools not only speeds up the work but also more effectively balances the tool loading on the ingot since the resistance of each tool tends to fluctuate in value in cutting metals of variable hardness.

When the scalping operation is completed, the ingot is returned to its lowermost position, and the upper ram is then raised out of the way for removal of the work piece. The upper ram is raised by rotating valve 80 a quarter turn counterclockwise from its FIGURE 2 position to connect pipe 45 with return pipe 93 and then closing valve 92 and opening valve 77 to admit fluid pressure under piston 38. 4

. 8 Modification in FIGURES 13 to 16 FIGURES 13 to 16 illustrate a modified arrangement in which the tool holder block rotates to place the plurality of tools in different cutting positions. Inthis modifica tion the lower piston assembly is the same as shown in FIGURE 2 except that worm 23 and worm gear 22 are omitted and ram piston 20 is secured to guide plate 27 whereby the work piece is held securely against rotation by the vertical guides 28. It is not necessary, however, to remove the worm 23 and Worm gear 22 from the machine of FIGURE 2 in order to install the' modified tool holder block since the worm itself constitutes a rotational lock for the work piece.

The work piece is stroked back and forth without turning, and, after each working cut, an annular tool holder block is rotated slightly in an annular channel 151 in the lower end of upper frame member 35. Tool holder block 150 is rotated by means of sprocket teeth 152 on its periphery engaged with an endless chain 153. Chain 153 is moved by a small sprocket wheel 154 on a vertical shaft 155 equipped with a hand wheel 156 or other suitable driving means.

Annular channel 151 is adapted to receive different types of tool holder blocks interchangeably according to the character of the work piece and the choice of the operator. The tool holder assembly has been omitted from the channel 151 in the left side of FIGURE 13 in order to show more clearly how the channel is arranged to accommodate the complete tool holder assembly as a detachable and interchangeable unit. One form of tool holder assembly will be described in detail.

The tool holder block is indexed to each new cutting position by means of a second ring of peripheral teeth or notches 157 arranged for engagement by a lock pin 158. The inner end of lock pin 158 forms a piston in a cylinder 159 into which fluid pressure may be introduced by pipe 160 to extend the lock pin. A stem on the lock pin is equipped with a spring 166 to retract the lock pin when fluid pressure is relieved from cylinder 159.

Each individual cutting tool 50 is secured in a tool holder comprising a clapper box 170 mounted on a pivot 171 in tool holder block 150 and including a tail piece 172. Directly above tail piece 172 is a cylindrical bore 173 in the tool holder block containing a piston 174. When fluid pressure is introduced into cylinder 173, piston 174 is driven downward to engage tail piece 172 and hold the clapper box up against the under side of tool block 150 so that tool 50 is placed in horizontal position for a cutting stroke, as shown in FIGURES 13 and 15.

When fluid pressure is relieved from cylinder 173, the weight of the clapper box 170 and tool 50 causes these parts to drop to an inclined position, as shown in FIG- URE 16, so that the tool will clear the work piece when the work piece makes its return stroke downward. If the clapper boxes do not drop by gravity, they are pushed out of the way by the descending work piece, it being remembered that the bottom end of the work piece finishes its upward working stroke at a position slightly above the level of tools 50.

In order to provide for rotation of annular tool holder block '150, the channel 151 is lined with three stationary bearing rings 180, 181, and 182 of suitable bearing material. Rings and 182 are secured to frame member 35 by screws (not shown) through their horizontal flanges. Tool holder block 150 is retained in the bearing rings by suitable retaining means (not shown) which permit its convenient removal for interchangeability as above mentioned.

Each cylinder bore 173 communicates with a radial duct 183 leading to an annular channel 185 extending around the outer periphery of the rotatable tool holder block 150. Hydraulic fluid is introduced into channel.

openings in frame members and 35 and bearing ring 180, 'asshown. These details are shown inFIGURE 15.

Fluid pressure pipes 160 and 186 may be supplied from'o'ne of the pumps 70 or 71 in lF' IGURE 2 or from a separate source of pressure under control of suitable valves. When fluid pressure is applied to pipe 186, all the clapper boxes 170 are moved to working position, as ShJOWll in FIGURES l3 and 15, and when fluid pressure is relieved from pipe 186, all the clapper boxes are free to drop to non-working position, as shown in FIG- URE 16. Suitable seals such as rubber O-rings (not shown) may be installed in tool holder block 150 above and below channel 185 to prevent leakage of hydraulic fluid from this channel.

Rotatable tool holder block 150 is illustrative of a suitable type of cross feed for cylindrical work pieces. In a somewhat similar manner the individual tool holders may be provided with a suitable horizontal cross feed mechanism for removing the surface imperfectionson polygonal billets, the work piece being reciprocated up and down by the pistons without rotation. In the BIG- URE 13 modification, the stroking cycle is the same as shown in FIGURES 8 to 11, but without turning of the work piece. The cutting pattern is similar to FIG- URE 12 except that more cuts are made in each stroke.

. In all'cases the entire lateral surface may be finished in a single operation without re-locating the work piece in its holding shoes. By reason of the fact that the work piece is supported at its ends by holding shoes of smaller size that the end areas of the work piece, all longitudinal surfaces of the work piece are available for cutting. When the work piece is cylindrical, relative circumferential tool feed may be obtained either by rotating the work piece as shown in FIGURE 2 or by rotating the tool holders as shown in FIGURE 13.

The present arrangement permits the use of a relatively large number of tools operating simultaneously to remove the surface of a large ingot or a billet in a relatively short time. The tool holder block 150 in FIG- URES 13 and 14 carries twelve clapper boxes 170 each holding one tool 50.

In the present machine there is no tool feed toward the work piece because the tools plow to the full depth of the material to be removed in each out. However, infeed means acting on all the tools simultaneously may be provided, if desired, as, for example, in removing the taper from a slightly tapered ingot. Suitable adjustment is, of course, provided in any event to position the tools and advance them in compensation for wear as by individual adjustment screws 175 and clamp screws, not shown.

It will be appreciated that the present machine has no bearings or guide surfaces subject to excessive loading to produce objectionable deflection or friction, either by the weight of the work piece or the tool force exerted thereagainst. The weight of the work piece, as well as the clamping pressure applied thereto, are sustained directly by the hydraulic fluid in the cylinders by reason of the vertical position of the cylinders. Lateral, as well as longitudinal, tool pressures are substantially balanced on opposite sides of the work piece. Hence, any deflection or distortion that may occur in the machine is symmetrically applied and distributed about the axis of the work piece in both longitudinal and transverse directions without aifecting the relationship of the tools to the work.

This is in distinct contrast to a conventional lathe operation, for example, where the work piece is supported by bearings which must additionally sustain eccentric loading applied usually by a single tool. Also, in a lathe, if the chucks are arranged to exert axial clamping pressure on the ends of the work piece, this force likewise introduces additional loading on the bearings.

The present supporting and moving mechanism for the work; piece and the Symmetrical mounting arrangement of the cutting tools provide such extreme rigidity against longitudinal, transverse and torsional movements and deflections that the tools can successfully remove-materials at a much faster rate than in conventional machines. Conventional work piece and tool holding arrangements produce chattering and short tool life when high cutting The mode of material removal in the present machine is characterized as a deep plowing action at low cutting speed and very high tool forces wherein a greater volume of material is removed in unit time by each tool than can be removed by a lathe tool, particularly in the case of refractory metals. In order to accomplish this result the individual unit tool forces provided in the present machine are twenty-ifive or more times those provided in a conventional lathe. Although the cutting speed may be only one-tenth the cutting speed of a lathe, the thickness of material removed in each cut may be twentyfive, or more, times the thickness of material turned off by aiathe in terms of feed rate. Thus, in unit time, each tool may remove two and one-half, or more, times the volume of material removed by the same tool in a lathe. As a practical example of the efliciency of the present machine, a titanium ingot 30 inches in diameter and 96 inches long usually requires 16, or more, hours for scalping on a lathe. The same job can normally be done on the present machine in less than one hour using 12 cutting tools operating simultaneously, and the saving in time is only one of several advantages gained. There are also savings in power, tool wear and general wear on the machine.

The advantages of the present method and apparatus are strikingly demonstrated in the scalping and surface conditioning of ingots and billets of the refractory metals and super alloys. In the case of titanium, ziroconium and the other refractory metals, for example, it is dilficult or impossible to use conventional grinding methods for removing surface imperfections. or billets of such metals, as well as the super alloys known in the trade as M-25Q, A-286, Waspaloy, and others,

are diflicult or impossible to scalp in a conventional lathe. Such ingots and billets have a surface skin consisting of hard and abrasive constituents in the case of the refractory metals, and super hard martensitic particles in the case of the super alloys, as well as discontinuities, porosities and, in the case of air-cast ingots and billets, inclusions from the mold surface. All of these elements in varying degrees act to create a hard, tough and abrasive skin surface which, unlike the parent metal beneath the surface, resists conventional cutting methods and causes cratering destruction of the tools.

These difliculties are overcome in the present machine by the deep plowing action of a plurality of tools operating simultaneously on opposite sides of the work piece in balanced loading with rectilinear movement of the work piece in a massive and rigid supporting structure. Ingots and billets of the above-mentioned refractory metals and super alloys are successfully scalped and surface conditioned in the present machine. In the case of ordinary steels, the invention offers the advantages of speed and economy over conventional methods and apparatus.

Notwithstanding the various advantages herein assigned to vertical chucking and vertical feed movement of the work piece, it is, nevertheless, within the scope of the invention to mount the cylinders horizontally for horizontal reciprocation of the pistons and work piece. It

Further, ingots aosaoe 11 is recognized that there are also certain horizontal arrangement.

' .Having now described my invention and in what man.- ner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. Apparatus for machining a work piece comprising a pair of holders aligned on an axis of reciprocation to engage opposite ends of the work piece, opposed fluid pressure actuated pistons connected with the respective holders, a fluid pressure system including a source of fluid pressure and means for applying adjustable fluid pressure to said pistons to force the holders toward the work piece and thereby to clamp the same between the holders, said holders constituting the sole support for said work piece, means in said fluid pressure system controlling the fluid pressure on at least one of said pistons to cause reciprocal motion of said holders, said first named means serving to continue application of clamping force to the work piece during such reciprocation, tools arranged to make axial cuts simultaneously on opposite sides of the work piece when the work piece is reciprocated, and means for effecting incremental relative rotation between said tools and work piece about said axis between successive working strokes of the work piece.

2. Apparatus for machining a work piece comprising a pair of holders aligned on an axis of reciprocation to engage opposite ends of a work piece, opposed hydraulic pistons connected with the respective holders, an hydraulic system including a source of hydraulic pressure and means for applying hydraulic pressures to said pistons to clamp the work piece between said holders, said holders constituting the sole support for said work piece, means in said hydraulic system controlling the hydraulic pressures on said pistons to cause one holder to advance in each direction of stroke and push the other holder in retreat, means for maintaining hydraulic back pressure against the piston of the retreating holder to clamp the work piece against the advancing holder in both directions of stroke, tools arranged to make axial cuts simultaneously on opposite sides of the work piece when the work piece is reciprocated, and means for effecting incremental relative rotation between said tools and work piece about said axis after a working stroke of the work piece.

3. Apparatus as defined in claim 2, said means for maintaining back pressures against said pistons comprising pressure relief valves connected to control the displacement of hydraulic fluid by retreat movement of said pistons.

4. Apparatus as defined in claim 2, said means for maintaining back pressure further including said means for applying hydraulic pressures to said pistons from said source of hydraulic pressure.

5. Apparatus for holding and reciprocating a work piece comprising a pair of holders aligned on an axis of reciprocation to engage opposite ends of the work piece, opposed hydraulic pistons connected with the respective holders, an hydraulic system including a source of hydraulic pressure and means for applying hydraulic pressures to said pistons, and means for controlling the application of said pressures to said pistons causing one holder to advance and push the other holder in retreat in a stroke in one direction and then causing said other holder to advance and push said one holder in retreat in a stroke in the opposite direction, said controlling means further including means for maintaining hydraulic back pressure against the piston of the retreating holder to clamp the work piece against the advancing holder in both directions of stroke.

6. Apparatus as defined in claim 5, one of said pistons being a double acting piston for retraction to unclamp the work piece.

7. Apparatus as defined in claim 5, said source of hydraulic pressure comprising a first source for actuating advantages in a the piston for one or said holders and a second source for actuating the piston for the other holder.

8. Apparatus as defined in claim 2, said rotating means being operable on one of said holders to rotate the work piece.

9. Apparatus as defined in claim 2, said rotating means being operable on said tools.

10. Apparatus as defined in claim 2, one of said holders moving the work piece in a working stroke and the other holder moving the work piece in a non-working return stroke, the piston area for producing said'working stroke being greater than the piston area for producing said return stroke.

11. Apparatus as defined in claim 10, said axis of reciprocation being vertical, said one holder having the larger piston area clamping the bottom of the work piece and said other holder having the smaller piston area clamping the top of the work piece.

12. Apparatus as defined in claim 2, the piston connected with one of said holders being a single acting piston and the piston connected with the other holder being a double acting piston.

13. Apparatus for machining a work piece comprising a pair of holders aligned on an axis of reciprocation to engage opposite ends of a work piece, opposed hydraulic pistons connected with the respective holders, a source of hydraulic pressure operable on said pistons to clamp the work piece between said holders, said holders constituting the sole support for said work piece, an hydraulic system having valves for controlling the hydraulic pressures on said pistons to reciprocate said pistons with said work piece clamped therebetween, tools arranged to make axial cuts simultaneously on opposite sides of the work piece when the work piece is reciprocated, and means for cffecting incremental relative rotation between said tools and Work piece about said axis after each working stroke of the work piece, said source of hydraulic pressure including means for applying different hydraulic pressures to the pistons for the two holders and for varying the values of said pressures individually, and said hydraulic system including valves for disconnecting the source of hydraulic pressure from said pistons selectively and means for maintaining predetermined back pressures against said pistons when said source is disconnected and for varying the values of said back pressures individually.

14. Apparatus for machining a work piece comprising a pair of cylinders in vertical axial alignment, a single acting piston in the lower cylinder and a double acting piston in the upper cylinder, opposed work holding shoes on said pistons for clamping the ends of a work piece, a source of hydraulic pressure, an hydraulic system having pipe connections with said cylinders for applying hydraulic pressures from said source to said pistons for clamping a work piece between said holding shoes, valves in said system for controlling the application of hydraulic pressures to said pistons to reciprocate said pistons with said work piece clamped therebetween, means in said system for maintaining hydraulic back pressure on the retreating piston in each direction of reciprocation, a tool holder having axial cutting tools operable on opposite sides of the work piece when the work piece is reciprocated, and means for turning the work piece in incremental rotation relative to said tools after each working stroke of the work piece.

15. Apparatus as defined in claim 14, said turning means being operable on one of said pistons to rotate said piston in said cylinder.

16. Apparatus as defined in claim 14, said turning means being operable on said tool holder to rotate said tool holder about the axis of said cylinders.

17. Apparatus as defined in claim 14, said means for maintaining back pressures on said pistons comprising pressure relief valves controlling the discharge of hydraulic fluid displaced by the retreating piston.

18. Apparatus as defined in claim 14, said lower cylinmemes der and piston being of larger diameter than said upper 1,973,801 Dustan Sept. 18, 1934 cylinder and piston. 2,127,210 Dunbar Aug. 16, 1938 19. Apparatus as defined in claim 14, said source of 2,345,973 Harrington Apr. 4, 1944 hydraulic pressure comprising a first source connected to 2,399,824 Pressman May 7, 1946 said lower cylinder and a second source connected to said 5 2,596,772 Hawkes May 13, 1952 upper cylinder. ,5 2,787,698 Schlatter Apr. 2, 1957 2,875,718 Bieri Mar. 3, 1959 References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS 1 573 454 1 752,717 Great Britain -1.- July 11, 1956 Shut 16, 1926 906880 Germany Mar. 18 1954 1,956,618 Kamp May 1, 1934

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