US2572953A

US2572953A - Floating press head

Info

Publication number: US2572953A
Application number: US45113A
Authority: US
Inventors: Thomas A Saari
Original assignee: Baldwin Lima Hamilton Corp
Current assignee: Baldwin Lima Hamilton Corp
Priority date: 1948-08-19
Filing date: 1948-08-19
Publication date: 1951-10-30
Anticipated expiration: 1968-10-30

Description

Oct. 30, 1951 T. A. sAARl 2,572,953

FLOATING PRESS HEAD NI Y INVENTOR. #l Thomas A. 50G/'v' Oct. `30, 1951 T. A. sAARl 2,572,953

FLoATING PRESS HEAD Filed Aug. 19, 1948 4 sheets-sheet 2 f3 5 49 Y/ l /75 F1 l7. E- INVENToR.

Thomas AScfar/ Oct. 30, 1951 T. A. sAARl 2,572,953

nom-ING PRESS HEAD Y Filed Aug. 19. 1948 4 sheet's-shet 3 Patented Oct. 30, 1951 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to presses and in particular to mechanismnthat at least in part is hydraulic in nature and that may be used with a crank-operated press to provide a dwell or interval of time during the stroke of the press during which time a substantially constant pressure is exerted on the material being pressed.

Crank-operated presses have been 4used for many operations including the compacting of plasticpowders in the production of preforms for use in compression molding. While some plastics in powder form may be satisfactorily compacted in a crank-operated press, other plastic powders require that the pressure be maintained for an appreciable length of time. An ordinary crankoperated press, since the travel of the ram is determined by the crank throw, can not apply a steady pressure without actuall-y stopping the crank with the ram in contact with the material. This type of operation, however, is impractical, if not impossible, because a heavy flywheel is employed to store energy which is delivered to the ram during the compacting stroke. As long as a ywheel is employed in this manner the crank can not be readily started and stopped during each revolution.

The principal object of this invention is to provide a hydraulic mechanism that acts preferably between the crank-operated head of a press and the ram vwhich applies the pressure to the material being compacted and Which hydraulic mechanism serves to maintain a constant pressure on the material being compacted during an appreciable portion of the stroke of the press.

Another object of the invention is to provide a relief mechanism in the moving head of a crank.- operated press which relief mechanism permits relative movement between the ram of the press and the moving head when the force exerted Yby the ram exceeds a predetermined limit.

A still further object of the invention is to provide in the moving head of a crank-,operated press a plurality of axially aligned cylinders| at least some of which are equipped with pistons and iilled Wtih hydraulic iiuid.

Another object of the invention is to provide a hydraulic cylinder in the moving head of va crankoperated press and arranging that cylinder so that it acts as a lpump and by pumping fluid against a predetermined back pressure determines the maximum force with which themoving head acts against the ram.

A still further object of the invention is to provide a hydraulic cylnderin the moving Vhead of a crank-operated press, which :cvlinderl-,s ,conf

nected to a source ofv hydraulic fluid that is maintained under a predetermined pressure so that the maximum force with which the head acts against the ram is vlimited and Which by providing relative movementbetween the ram .andthe movine head permits an extension lof the time .during which the ram acts against the material being DTSSSCI- More speeic objeetsand advantages are apparent from the following description in which reference is made to the accompanying drawings illustrating preferred embodiments of the inver;- tion.

In the drawings; l

Figure I is a front yelevation of a crank-operated press the head of which is provided with a hydraulic cylinder according to the invention.

Figure II is anV enlarged vertical section of the hydraulic cylinder assembly that is mounted on the moving head of the press shown in Figure I`- Figure III is a vertical section of an indicator and limit switch operating mechanism that is employed to supervise the operation of the hydraulic cylinder.

Figure IV is a modiiication of the hydraulicy cylinder in which it acts as a self-contained pump to limit the maximum force that is exerted by the ram.

Figure V is a vertical section of a modified form of structure embodying the invention.

Figure VI is a diagrammatic illustration of the hydraulic connections to the mechanism illus-.1 trated in Figure V.

Fig-ure VII is a vertical section ,of still another embodiment of the invention.

Figure-VIII is a diagrammatic sketch showing the hydraulic connections .for the hydraulic cylinder shown in Figure These specific -gures and the accompanying description are intended merely to illustrate the invention but not to impose limitations on the claims.

Referring now to the accompanying drawings, a crank-operated press in which the invention may be advantageously Aemployed includes a-base I within which is mounted crank mechanismgfor reciprocating tie rods 2 that support a head mechanism 3. The cra-nk mechanism is conventional and is driven by a motor or other suitable source of power that is not shown.

The crank mechanism v-vvithin the base l is also arranged to reciprocate a lower punch that serves as the bottom ofthe die'cavi-ty of the pressfand that also serves to eject-the compacted article'at the nish of each stroke.y The height and travel 'of the lower punch is controlled by a hand wheel 4 that is carried on a shaft protruding from the front of the base I.

The head mechanism 3 includes a cylindrical portion the upper part of which forms the body of a hydraulic cylinder. Above the cylindrical portion 5 is a necked-down section 6 and a second cylindrical portion 1 which, in this embodiment of the invention, is the housing of an air cylinder.

Referring now to Figure II, the head mechanism 3 includes a platen 8 to which a ram may be attached. The platen 8 is supported against upward movement by a heavy externally-threaded sleeve 9 the threaded portion of which engages an internally-threaded sleeve I8 the upper end of which is press-fitted into a recess in a piston I I, which in turn is slidably mounted within the upper cylindrical portion of the casing 5. To prevent rotation, the platen 8, which is circular in plan, has a keyway I2 that cooperates with a key I3 secured in an annular insert I4 fitted into the bottom open end of the head portion 5. Likewise, the piston I I and the press-fitted internallythreaded sleeve I8 are prevented from rotating by the cooperation of a spring-pressed key I5 and a vertical slot I6 cut in the side of the internallythreaded sleeve III.

A bolt I1 the lower end of which is secured to the platen 8 extends axially through the heavy sleeve 9 with its head I8 contained within a counterbore I9 at the upper end of the heavy externally-threaded sleeve 9. The bolt I1 serves to support the platen against the lower end of the heavy sleeve 9. A ring 20 slidably mounted on the heavy sleeve 9 is keyed to the sleeve and is held in position between theupper surface of the annular insert i4 and the lower surface of the internally-threaded sleeve I8. Rotation of the ring 20 serves to screw the heavy sleeve 9 into or out of the internallythreaded sleeve IIJ to adjust the height of the platen 8 with respect to the head mechanism 3.

The ring 28 is provided with gear teeth 2I that mesh with a pinion 22 that is carried on a vertical axle 23 the lower end of which is journaled in a hole drilled in the upper surface of the annular insert I4 and the upper end of which is journaled in a hole drilled in an inwardly-directed flange 24 of the cylindrical head portion 5. The hub of the pinion 22 is formed with bevel gear teeth 25 that mesh with a bevel gear 26 carried on the inner end of'a shaft 21 the other end of which is provided with a hand wheel 28. The shaft 21 is carried in a long cylindrical bearing 29 that is set into the side of the circular head portion or casing 5.` Rotation of the hand wheel 28 acting through vthe bevel gear 26, pinion 22, and the ring 20 .serves to adjust the height of the platen 8. The hand wheel 28 is xedly held in adjusted position by a lock controlled by a laterally extending handle 30 located adjacent the hand wheel 28.

The piston I I is slidably contained within a cylindrical bore 3l of the head portion 5 and is provided with suitable packings 32 and a cover plate 33 for holding the packings 32 in place. The space between the upper plate 33 of the piston I I land a cover 34 closing the top of the bore 3I is filled with hydraulic fluid under pressure for urging the piston II down against the inwardly-directed flange 24. Any fluid that leaks past the packing members 32 is collected in an annular trough 35 and drained from the trough through a downwardly-inclined hole 38 leading to the outside of the head portion 5.

4 The necked-down portion 6 is provided with a small diameter hydraulic piston 31 the upper end of which is attached to a large diameter piston 38 slidably mounted within the upper cylindrical portion 1 of the head mechanism 3. The large diameter piston 38 includes a bottom plate 39 into which a tenon of the small diameter piston 31 is secured, a sealing diaphragm 40 and an upper plate 4I that holds the diaphragm 40 in position against the lower plate 39. Air under pressure is admitted through a pipe 42 secured into a cover 43 that closes the upper end of the cylindrical section or air cylinder 1. The pressure of the air admitted through the pipe 42 acting against the upper surface of the air piston 38 drives the small diameter hydraulic piston 31 downwardly through the necked-down portion 6 so that the small diameter hydraulic piston 31 exerts pressure within the chamber over the piston II. Leakage of fluid past the small diameter hydraulic piston 31 is prevented by sealing rings 44 installed in the upper end of the necked-down portion 6. 1 In this assembly, as the head of the press moves down and a ram connected to the platen 8 engages the material to be compacted, the force acting against the platen 8 increases until finally that force exceeds the force exerted by the hydraulic fluid against the piston II so that the piston II lifts with respect to the head mechanism 3.- As it rises it forces the small diameter hydraulic piston 31 upwardly through the neckeddown portion 6, thereby either compressing the air within the air cylinder or driving the air out of the cylinder to an accumulator or through a pressure relief valve. As the head of the press reaches the bottom of its stroke and starts upward the compressed air within the air cylinderf1 still urges the piston down thereby driving the small diameter hydraulic piston 31 and the piston II downward to maintain the pressure applied to the ram even though the head of the press is moving upwardly. The pressure against the ram is maintained until the bottom of the piston II again comes to rest on the inwardly-directed flange 24. The pressure exerted by the ram against the work may be easily controlled by adjusting the air pressure within the air cylinder. The air pressure need not be extremely high because a great multiplicationof force results from the differences in piston areas of the hydraulicV and air pistons. As a check on the operation of the air piston 38 and incidentally as a measure of the quantity of hydraulic fluid contained in the chamber over the piston II, the air piston 38 is provided with an indicator rod 45 that extends up through a packing gland 46 and which at its upper end carries an indicator arm 41 (Figure III). The indicator arm 41 projects laterally from a guard 48 that is erected from the air cylinder cover 43. A pair of

limit switches

49 and 58 may be included in the guard 48 and connected to auxiliaryfequipment suitable for supervising the operation of the press. l Y

In normal operation of the mechanism, the indicator arm 41 never strikes or actuates the lower limit switch 49 because the downward movement of the air piston 38 and small diameter hydraulic piston 31 is checked when the large hydraulic piston II strikes the inwardlydirected flange 24. The normal quantity of hydraulic uid contained within the chamber holdsV the air piston 38 above the bottom possible limit of its travel so that pressure is maintained onA the hydraulic fluid -at all times. If hydraulic`l fluid leaks from the chamber Vthe air piston 35 settles and eventually the limit switch 43 is actuated to give an indication that `the hydraulic fluid must be replenished.

In normal operation of the device the air piston 38 is never driven to its upper limit of travel but'such movement may result if, for some reason Vsuch as failure to reject a previously compacted article, an excessive amount of material isrbeing compacted under the ram. In this event the pistons are .forced to their upper limits of travel and the indicator arm 41 is driven against the upper limit switch 59 which switch may be connected .to activate a safety device such as a throw-out clutch effective to immediately stop the operation of the press.

This structure is relatively simple to adj-ust in that the maximum pressure is controlled entirely by the air pressure maintained within the air cylinder 1 and that there is only one set oi cylinders to be maintained in operative condition so there is not question of balance between various elements. Furthermore, the parts are all simple and easy to construct.

Figure IV shows a modification of the upper portion of the head mechanism in which a hy-V draulic cylinder 5| is substituted for theair cylinder 1. In this example a small diameter hydraulic piston 52 which corresponds to the small diameter hydraulic piston 31 of Figure II carries a larger piston 53 on its upper end. The piston 53 is urged downwardly within the cylinder 5| by a heavy conical spring 54 that is held compressed between the upper surface of the piston 53 and a cap 55 of the cylinder 5|. When the piston 53 moves up as a result of pressure applied to the ram by downward movement of the head mechanism the tension of the spring 54 is overcome and hydraulic fluid within the cylinder 5| is forced out through a spring loaded pressure relief'valve 56 which valve discharges through a pipe 51 into a reservoir 58. The pressure maintained by the relief valve 5S is sufficient to supply the required force at the ram.

When the press head mechanism moves upwardly after a compression stroke and the pressure on the ram is released the spring 54 drives the pistons down and the hydraulic iluid is drawn from the reservoir 58 through a check valve 59 into the hydraulic cylinder 5|.

This arrangement is self-contained in that it requires no external source of air yor fluid under pressure but it has the disadvantage that it does not maintain pressure on the material being compacted during the initial upward movement of the head mechanism in a manner corresponding to the pressure exerted as a result of the expansion of the air within the air cylinder 1. This follows because the pressure within the hydraulic cylinder 5| must be reduced below atmospheric pressure before the check valve 59 can open to admit hydraulic fluid from the reservoir 58 and allow the piston 53 to descend.

Another example is illustrated in Figures V and VI. In this example a head mechanism 6B that is carried on tie rods 5| includes a cylindrical casing 62 forming a cylinder in which a hydraulic piston 63 is slidably mounted. The piston 63 is provided with packing means 64 that are held in place by an upper piston plate 55. The piston 63 is urged downwardly within the cylinder 62 by a heavy helical spring 66 that is held compressed between the upper piston plate 65 and a cap 61 closing the upper end of the cylinder. The downward travel of the piston 63 is 'limited 'by an annular inwardly-directed flange 68 that engages the outerportion of the under surface of the piston 63. An annular groove -69 out `at the outer edge of ythe annular flange 68 collects any hydraulic fluid that may leak past the packing means'sl and this leakage nfluid is drained through a duct 10 leading to the outside of the cylinder 62.

The piston 63 has an integral downwardlydirected internally-threaded sleeve portion 1| that is guided through the flange |58 and vinto which is screwed an externally-threaded heavy sleeve 12. A bolt or stud 13 that is fitted with a nut 14 set in a counterbore at the upper end of the heavy externally-threaded sleeve 1-2 ,is threaded into a .platen 15 and serves to support the platen against the lower end of the heavy sleeve 1'2. The platen 15 is guided in an annular insert 16 set in the lower end of the cylinder r`62 and is prevented from rotating therein by a Ykey 11 that engages a slot 18 milled in the periphery of the platen 15. The piston 53 is also prevented from rotating'within the cylinder 92 by a vertical pin 19 that fits into holes drilled in the uppersurface of the inwardly-'directed flange 68 and the lower surface of the piston 93.

Adjustment of the height of the, platen 15 is accomplished by rotating the heavy sleeve `12 with respect to the piston 63 and for this purpose the sleeve 12 is provided with a ring o'f gear 'teeth that mesh with an elongated pinion 8|. The pinion 8| at one end is formed with bevel gear teeth 82 vthat are engaged byl a vbevel gear 83 mounted on the inner end of a vshaft 84`the outer end of which carries a hand wheel 85. A lock 86 serves to hold the hand wheel in adjusted position and thus maintain the lower position of the platen 15 with respect to the head mechanism 6|).

As the head mechanism moves downwardly to compact material within a die and a ram attached to the platen 15 applies a preselected maximum force to the material, the piston 63 moves upwardly within the cylinder`62 thereby compressing the spring 66 and at the same time forcing a small hydraulic piston 81 upwardly through a necked-'down portion' of the head mechanism 60. The small diameter hydraulic piston 81 carries a large diameter piston 89 on its upper end and the piston 89 is slidably mounted within an upper cylinder 9|).

`Referring t0 Figure VI, the upper cylinder 90 is connected through a liexible hydraulic lead 9| and a small accumulator 92 to a source of pressure that serves to maintain a constant pressure within the cylinder regardless of changes in volume. A pressure gauge 93 may be employed to indicate the pressure within the cylinder 99.

In this example, as in the preceding examples, a portion of the head mechanism is yieldably held in the head mechanism so that the force applying member or ram vmay remain stationary during an appreciable portion of the stroke of a crankoperated press. In each of these examples a plurality of hydraulic cylinders or hydraulicl and pneumatic cylinders are arranged in axial alignment in the head mechanism of the press. This arrangement is extremely simple to manufacture and very serviceable in use.

Still another example of a crank-operated press head mechanism embodying the invention is illustrated in Figures VII and VIII. p

In this example a head mechanism 94 is'supported on crank-operated tie rods 95 arranged to reciprocate the head in a vertical direction. The head mechanism 94 includes a hydraulic tom peripheral portion 98 engages an inwardlydirected flange 99 of the cylinder 96. The piston 91 is provided with packings |00 that, being held in place by a piston top plate serve to prevent the leakage of hydraulic fluid past the plston. Any seepage of hydraulic uid past the piston is collected in an annular trough |02 and drained through a drain |03.

The underside of the piston 91 is provided with a downwardly-directed internally-threaded sleeve |04 which is guided in a bushing |05 set in the inwardly-directed ange 99 and which, to prevent rotation of the piston, is provided with a keyway |06 that cooperates with a spring-pressed key |01.

A heavy externally-threaded sleeve |08 that is threaded into the internally-threaded sleeve |04 supports a platen |09 against upward movement. The platen |09 is held against rotation by a key ||0 set into the bottom surface of an annular insert heavy sleeve |08 and supports an annular gear |2 that is slidably keyed to the heavy sleeve |08. The platen |09 is held up against the heavy sleeve |08 by a stem I3 that extends upwardly through the heavy sleeve with a nut I4.

This arrangement of elements permits the height of the platen |09 to be adjusted with respect to the hydraulic cylinder 96 by rotation of the heavy externally-threaded sleeve |08 within the piston sleeve |04. This rotation of the sleeve is accomplished by'a hand wheel ||5 carried on the end of a shaft I |6 the inner end of which carries a bevel gear ||1 meshing with beveled gear teeth ||0 formed on the upper end of a pinion hub ||9. The pinion hub ||9 has a pinion |20 meshing with the annular gear ||2 and is supported on a vertical shaft |2| the upper end of which is journaled in the inwardly-directed ange 99 and the lower end of which is journaled in the annular insert The piston 91 is yieldably held in its lowermost position within the head mechanism 94 by hydraulic fluid held in the space above the piston. When the load applied to the platen |09 during the compacting of material within the press exceeds the pressure of the hydraulic fluid some of the uid is forced from the hydraulic cylinder thus permitting the platen |09 and piston 91 to move upwardly with respect to the head mechanism 94. During this upward movement a steady pressure is maintained on the material being Acompacted even though the head mechanism 94 is still moving downwardly. It is to be remembered that the head mechanism 94 is actuated by a crank mechanism and, therefore, executes a positively determined movement and that the pressure applied to the material being compacted except for the influence of the hydraulic cylinder is determined entirely by the quantity of 4material within the die of the press. The hydraulic cylinder modifies this relationship by setting a maximum pressure that can be applied and permitting relative motion between the platen and the head mechanism as soon as the predetermined pressure is reached.

The mounting for the slide connector |23 includes a pair of arms |32 projecting laterally from the head mechanism 94 and embracing an arm |33 that projects laterally from the sleeve |25. A bolt |34 threaded through the ends of the arms |32 and the arm |33 holds the parts in assembled relationship while permitting a small amount of play so that the sleeve |25 may accurately follow the plunger rod |26 without excessive friction or binding.

Since the plunger rod |26 projects from each end of the sleeve |25 the hydraulic pressures are balanced and there is no tendency for the hydraulic pressure to generate a force in the slide connector tending to raise or lower the head mechanism 94.

Referring now to Figure VIII, the conduit |24 is connected through a pressure regulator |35 to a conduit |36 leading to a source of hydraulic fluid that is maintained under high pressure. The conduit |24 is connected through a branch conduit |31 to a pressure relief valve |38 the discharge of which is led through a conduit |39 and back to the pump that maintains pressure on the conduit |36. In this arrangement the pressure relief valve is set to discharge fluid when the pressure in the cylinder 96 and the conduit |24 or |31 exceeds by a small margin the pressure for which the regulator |35 is set. With this adjustment the piston 91 is urged downwardly within the cylinder- 96 until it reaches its lower limit of travel and the pressure within the cylinder and within the conduits |22 and |24 is equal to the pressure at which the pressure regulator |35 is set.

During a pressing cycle, when the force exerted by the platen |09 exceeds the force exerted by the hydraulic fluid against the upper surface of the piston 91, the piston 91 rises within the cylinder 96 and fluid is discharged through the relief valve |38 as long as the hydraulic pressure within the system exceeds the pressure at which the relief valve is set. After the crank mechanism of the press passes its dead center position the flow of uid through the relief valve stops and the piston is urged downwardly within the cylinder 96 with a force proportional to the pressure supplied by the pressure regulator |35. As the head mechanism 94 moves upwardly to relieve the force applied to the materialbeing compacted, fluid flows from the source of pressure through the conduit |36 and the pressure regulator |35 to maintain the pressure of the platen |09 on the material until the piston 91 reaches its lower limit of travel with respect to the head mechanism 94. As the head mechanism 94 continues to rise, there is no further transfer 0f hydraulic fluid and the hydraulic system maintains itself in readiness for the next cycle of operation.

I'he improved press head mechanism including a hydraulic cylinder and a pressure controlling mechanism offers many advantages over a conventional crank-operated press. Among these advantages is the possibility of maintaining pressure on a material being compacted throughout an appreciable portion of the cycle of operation so that a Wider variety of materials, particularly those requiring a sustained pressure, may be handled by the press. Another important advantage is the freedom from the possibility of jamming the press by the accidental overlling of the die cavity because in such an event the piston and platen merely travel an additional distance without exerting excessive pressure against the parts of the press. In the event that the yieldable feature of the invention is not required the overload feature may be accomplished with very little extra expense by employing a self-contained hydraulic mechanism such as is illustrated in Figure IV and in such a mechanism setting the pressure relief valve 56 at a pressure slightly greater than that required for the normal operation of the press.

Various modications of the structure may be made without departing from the spirit and scope of the invention.

Having described the invention, I claim:

1. The combination in a crank operated press of the type having a mold cavity and a head mechanism that is reciprocated with a compression and a return stroke of xed length in a direc- `tion axially of said cavity, comprising, a ram for compressing material in said cavity, a cylinder in the head mechanism, a ram supporting member that is axially slidably mounted in said cylinder, means whereby the head and supporting member simultaneously move toward the cavity at the same speed and in a predetermined axially xed relation to each other until the ram starts to compress material in the cavity, means movable with the head mechanism for varying said xed axial relation of the ram so that different thicknesses of material may be compressed in the cavity, and means for maintaining a substantially constant hydraulic fluid pressure in said cylinder and against said ram supporting member so that on the compression stroke it can yield after engaging material in the cavity and on the return stroke its predetermined fixed relation can be re-established preparatory for the next compression stroke.

2. The combination set forth in claim 1 further characterized in that the ram supporting member includes a piston in the cylinder upon which the hydraulic iluid acts, and means for diverting from said cylinder any leakage of hydraulic fluid past said piston whereby material in the cavity is kept free of contamination from leakage uid.

3. The combination set forth in claim 1 further characterized in that the ram supporting means includes a piston in the cylinder, and the means for eiecting simultaneous movement of the head and ram supporting member includes opposed surfaces on said cylinder and piston engaging each other during the compression stroke until separated upon compression of the cavity material.

4. The combination set forth in claim 1 further characterized in that the ram supporting means includes a piston in the cylinder, and the means for eifecting simultaneous movement of the head and ram supporting member includes opposed radially extending surfaces on said cylinder and piston for engagementvwith each other during the compression stroke until separated upon compression of the cavity material, and means for diverting from said cylinder any leakage of hydraulic fluid past said piston including an annular groove formed at the end of the cylinder toward the mold cavity and surrounding said radial surfaces.

5. The combination set forth in claim 1 further characterized in that the ram supporting means includes a-piston, and the means for effecting simultaneous movement of the head and ram supporting member includes opposed annular surfaces on said cylinder and piston for engagement with each other during the compression stroke until separated upon compression of the cavity material, an annular groove formed at the end of the cylinder toward the mold cavity, said groove surrounding said annular surfaces and extending below the level thereof, and an annular portion on said piston projecting into said annular groove thereby providing a surface extending upwardly to the radial surface of the piston.

6. The combination set forth in claim 1 further characterized in that the ram supporting member includes an axially extending rotatable sleeve upon which the ram is mounted, and the means for varying the xed axial relation of the ram relative to the head includes a threaded connection between said sleeve and the remainder of the ram supporting member and gearing connected to said sleeve below said threaded connection for rotating the sleeve and thereby effecting axial adjustment of the ram.

7. The combination set forth in claim 1 further characterized in that the ram supporting member includes an axially extending rotatable sleeve, and the means for varying the xed axial relation of the ram relative to the head includes a threaded connection between said sleeve and the remainder of the ram supporting member, gearing connected to said sleeve below said threaded connection for rotating the sleeve and thereby effecting axial adjustment of the ram, said gearing including a gear encircling said sleeve and being relatively axially slidable but non-rotatable with respect thereto.

8. The combination set forth in claim 1 further characterized in that the ram supporting member includes an axially extending rotatable sleeve, and the means for varying the xed axial relation of the ram relative to the head includes a threaded connection between said sleeve and the remainder of the ram supporting member, a gear encircling the sleeve below said threaded connection for rotating the sleeve and thereby effecting axial adjustment of the ram, and gearing for operating said encircling gear having a shaft extending laterally from within the head mechanism to the outside thereof.

THOMAS A. SAARI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,687,995v Seabury Oct. 16, 1928 1,955,002 Irwin Apr. 17, 1934 2,128,152 MacMillin Aug. 23, 1938 2,150,097 Gunderson Mar. 7, 1939 2,219,048 Magnenat Oct. 22. 1940