US2362870A

US2362870A - Feed control

Info

Publication number: US2362870A
Application number: US368781A
Authority: US
Inventors: Loyd A Ward
Original assignee: TOMKINS JOHNSON CO
Current assignee: TOMKINS JOHNSON CO
Priority date: 1940-12-06
Filing date: 1940-12-06
Publication date: 1944-11-14
Anticipated expiration: 1961-11-14

Description

L. A. WARD FEED CONTROL Nov. 14, 1944.

2' Sheets-Sheet 1- Filed Dec. 6, 1940 1 5- L'UHJD AWARD L. A. WARD FEED CONTROL Nov. 14, 1944.

Filed Dec. .6; 1946 2 Sheets-Sheet 2 9 QN t M J H Hl l l M 1 MMMUH- WW A n D m N 5 Nm W 2 Q N 3.

/1II'III'II Patented Nov. 14, 1944 Loyd' A. Ward, Jackson Mioh assign'or to Tomkins-Johnson,Company, Jackson, Mich, a

t corporation of Michigan v H I 7 Application December 6, 1940, Serial No. 353,731

' 7 Claims. (Cl. .1ss 94') l The present invention relates to structure for controlling the rate ofmovementof a resiliently moved member and vmore particularly to a feed control for machine tools.

having a connection with a source .of compressed air for resiliently urging the hydraulic fluid from the reservoir .into the cylinder.

These and other. objects residing infthe rang'ement, combination and construction of the r e the end members It and H are clamped together parts will be apparent from the following specification when taken-with the accompanying drawings in which:

Fig. 1 is a plan view of acontrol according to the'present invention,

.7 Fig; 215. a partial section anthe line JII-II of In the automatic feeding of cutting tools; it is 5 desirable for several reasons "to employ com- Fig. 1,, the parts not in section beingshown in pressed air. However, the resiliencyoi a 'comelevation. l .f pressed air feed is undesirable in many cases, as Fig. 3 is a planvview of another control accord- -for'instance, in the "pneumatic feeding of a drill i g to thepresent inventiony r 1 I through a piece" of work. As the drill passes Fig. 4' is a partial Section on t e Y p et y t h' a piece of work, the release of Fig. 3;the parts not in section being shown of cutting resistance results in the drill being in elevation,

suddenly projected ahead, frequently with de- Fig. 5"is. a reversed section on the-line V-V structive consequences." According'to the pre's- Y ofFig.3, I ent invention; ap'neumatic' feed for machine tools Fig.6 is a section on the line VI-V'I of Fi is under the control'of ahydraulic' cylinder and Figs? is-an end elevation of another form of piston; attention being 'given to providing a slow .the invention, 1\ i I v feed and quick return; as well as to providing Fig. 8 isa partial section on the line VIII-47111 multiple advancing speeds providing for rapid of Fig. 7, the parts not in section being'shown in advance and slowieedover a single stroke. elevation;

' v 7 'An object of the inventionis to provide a feed Fig; 9 is an end elevation-of still another form control comprising a resilient actuator, and anyof'the invention, 1 f C 1 4 draulic rate of movement control. v r e Fig. 10 is a partial section on the lin'e'X'-X Another object of the invention is to provide lof Fig.9, the parts not in section being shown in a feed control comprising a pn eumatic actuator elevation, f and'a hydraulic cylinder and piston rate of move- Fig; 11 isa partial section on the line :XI-XI 'ment control. e LFig. 9', and 1 still an ther object of the invention is to pro- Fig. 12 is 'asectionljon' the line XII-XII of vide a hydraulic feed control arranged to mini Fig. 9! v mize interference of the control by airbubbles. in 'In' Figs. 1 and 2'of thedrawings, there is disthe hydraulic fiuiaip 7 ,closed'one form of the invention for-providing Still another objector the invention is toprorapid-advancing, slow feeding and rapid returnvide a hydraulic feed control consisting of a hying; Thereference character 1 indicates a pneuf draulic cylinder and piston, having associated .matic cylinder'hav-ing therein a piston 2 and a therewith a hydraulic fluid reservoir for main- '35 piston rod.3. The piston 2 is actuated by'suit- 'taining the cylinder filled with hydraulic, fluid able pneumatic controls,- not shown, and the pisduring all stages of operation. I ton rod 3 is operatively connected to some mech- A further object of the invention is to provide anismto beactuated, asfor instance, ,a machine 'a'hydraulic controliora resilient feed, wherein tool. T 9 v I a piston moves in a hydrau'lic chamber having a For, controlling. the rate ofmovement of the cylindrical'cooperating portion, and a portion of piston rod 3,fthe.pisto'n 2 has connected thereto larger diameter, vx' hereby the piston'may move a .pistonrod. 4, havinguon the outer end thereof freely in the chamber portion'of larger diameter, .a .p'istonifthe piston5 being smaller in diameter but must move at a controlled-rate in the cylingthan'th'e piston The piston 5 is disposed in a drical portion. g .hydraulicchamber 6. The chamber 6 is provided A still further object of the invention is to pro- 'with a cylindrical portion 1 for cooperating with 'vide a hydraulic cylinder andjpiston feed' control the piston 5 and an enlarged portion}! in which provided with a reservoir for -main tai ning the the piston 5 is freely movable. Between the encylinder filled with hydraulic fluid, the reservoir larged portion 8 and the cylindrical portion 1,

:the hydraulic chamber 6 is provided with a flared bellshaped portion 9. I

I The piston rod 4 extends through an end member [0 of the cylinder I and the end member H of the'hydraulic chamber 6. As shown in Fig. 2,

by cap screws |2. Surrounding the piston rod 4 in the end member ID is a packing ring l3, secured therein by a nut l4, and surrounding the piston rod 4 in the end member II are packing rings l5, secured therein by a nut l6.

Between the nuts l4 and I6 and disposed in the end member is an annular recess l1, connected by a vent l8 to the atmosphere. Thus, any air leakingbythe packing ring |3 from the pneumatic cylinder or any hydraulic fluid leaking by thepacking rings l from the hydraulic chamber 9 will be vented to the atmosphere and will prevent the entrance of any air from the pneumatic cylinder I into the hydraulic chamber 6.

Within the end member ll of. the hydraulic chamber 6 is disposed an annular space 22. The space 22 comprises an extension of the cylindrical portion 1 of the hydraulic chamber 6' and has" communicating therewith a port 23. The port 23 has connected thereto a. conduit 24 which is in turn connected to a valve 25, andthe valve 25 is connected with the enlarged portion 3 of the hydraulic chamber '5.

The operation of the structure just described is as follows: The hydraulic chamber 6 is provided with a hydraulic fluid up to the level125 for instance, leaving some suitable air space thereabove. As the piston 2 is moved downwardly in the pneumatic cylinder 1, the piston rod 4 moves downwardly moving with it the piston 5. Since the piston 5 freely moves in the. hydraulic chamber 6, in the upper portions thereof, there will be no retarding of the rate of movement of the piston 2 until the piston 5 moves into cooperating relation with the cylindrical portion 1 of the hydraulic chamber 6. Atthis point the hydraulic fluid in the cylindrical portion 1 will. be forced ahead of the piston 5 through the port 23,.the conduit 24 and the valve 25, the. valve 25 having been previously adjusted torestrict the passage of hydraulic fluid therethrough. to such an extent as to provide the desired rate of movement of the piston 5 and consequently the piston 2.

' As the piston 5 moves downwardly, a portion of the piston rod 4 moves out of the hydraulic chamber 6, thereby in ei'l'ect increasing the effective space therein. The air in the space above the level of the hydraulic fluid expands by an amount equal to the volume of the piston 4 moved outof the hydraulic chamber 5 to thereby permit the relatively unhampered movement of the piston 5.

When the piston 2 has reached the lower extremity of its stroke and consequently the piston 5 likewise, the piston 2 is returned toward the position shown in Fig. 2, moving through the piston rod 4', the piston 5. As the piston 5 starts its return movement, enough hydraulic fluid flows back through the valve 25, the conduit 24 and the port 23 and past the piston 5 to permit the piston 5 to move upwardly through the cylindrical portion 1 to the outwardly flared portion 9, at which point the hydraulic fluid from above rushes in behind the piston 5, without materially slowing the return of the piston 2. The valve 25 should communicate with the hydraulic chamber 6 at a point which is always below the level of the hydraulic fluid therein, so that upon the return movement of the piston. 5 no air will be drawn through the valve 25 and into the hydraulic fluid. The necessity for preventing air in the hydraulic fluid will be apparent when it is realized that any air bubbles therein which may be forced through the valve 25 on. feeding or downward movement of the piston 5 will result in irregular downward movement of the piston 5 and thus of the piston rod 3. 4

Another feature of the invention is that since the area of the piston 2 is greater than the area of the piston-5, the pressure to which the hydraulic fluid in the cylindrcial portion 1 is subjected after the piston 5 cooperates therewith will be greater than the pressure of the air in the pneumatic cylinder Thus, any tendency of leakage past the piston rod 4 will be in a direction from the hydraulic chamber 6 rather than toward the same. This tendency will insure against any air from the pneumatic cylinder leaking into the hydraulic chamber 6, although as a matter oi fact, as pointed out above, the vent f8 also provided for insuring against the leakage of air past the piston 4 into the hydraulic chamber 6. Another feature of the invention is that due to the increased pressure in the cylindrical portion 1 of the hydraulic chamber 6, any air bubbles that may accidentally get into the hydraulic fluid are compressed to such an extent that the effect of their passage through the valve is minimized.

Figs. 3 through 6 disclose another form of the invention, wherein a feed control is provided for averti'cally' movable pneumatic cylinder and piston, differing from the first. part of the invention, however, in that the slow feed is eflective throughout the entire forward movement of the pneumatic piston. and the quick return is provided by the use of a check valve rather than by the construction of the hydraulic chamber. The pneumatic cylinder I, together with its piston 2 and piston rod 3 are the same as in the first form of the invention and are for the same purpose. Likewise, the nd member IQ for the cylinder I is the same. The end member in is secured by cap screws l2 to an end member of a hydraulic cylinder 3|. The end member 30 also serves as an end member for a reservoir cylinder 32. surrounding the cylinder 3l- Disposed in the hydraulic cylinder 3| is a piston 33, similar to the piston 5. The pistons 2 and 33 are connected by a piston rod 34, which is reciprocable in the end members [0 and 30, which respectively are provided with packing rings l3 and I5, held in place by nuts l4. and I6, as disclosed in Fig. 2. Also, an annular space I! about the piston rod 34 is connected by a vent l8 to the atmosphere.

The end member 30 is provided with an annular space 3 5 comprising a continuation of the hydraulic cylinder 3|. Communicating with the space 35 is a port 36 connected to a valve 31, which is. in turn connected by a conduit 38 to the reservoir cylinder 32. The valve 31 constitutes a restricted adjustable orifice, similar to the valve 25 of Figs. 1 and 2..

A communication is provided between the hydraulic cylinder 3| and the reservoir cylinder 32 by a conduit 39., a check valve 411 and a conduit 4|. The conduit. 39 is connected to the annular space 35, as. shown particularly in Figs. 3 and 5, by a port 42, the. annular space 35 in turn having direct communication with the hydraulic cylinder 3|. The conduit 4|, as shown in Figs. 3 and 6, is connected to the reservoir cylinder 32 by ports 43 and 44 in member 30.

The reservoir cylinder 32 is connected at one end to the opposite end of the hydraulic cylinder 3| by a conduit 48, the conduit 48. communicating with the lower end of the reservoir cylinder 32 by port in. member 30, shown in Fig. 3 and being. similar to. the connection which. is used to connect conduit 38' with cylinder 32 as shown in In Figs.:7 and'8 another form of. the inven- 4. The conduit 48 is connected at its upper 7 tion' is shown.' This form of the invention is simiend to the hydraulic cylinder 3| by a port5l in a cap 52, constituting a cover'for the upper ends of the cylinders 3| and 32.- Ports 53 and'54- in the cap 52 are-connected by some suitable conduit means not shown to a sourceof compressed'air for directing compressed air into the reservoir cylinder 32. Q

In the operation of the form of the invention disclosedin Figs. 3 through 6, the hydraulic system is provided withhydraulic fluid, the hydraulic cylinder 3| being filled and the reservoir cylinder 32- being filled to some suitable level such as at "55. The

compressed air through'theports

53 and 54 maintains a pressure on the top of the hy- Y draulic fluid with the result that hydraulic fluid 'is forced from the reservoir cylinder 32 through the ports 50 and 49, the conduit 48 andthe port 51 into the top of the hydraulic cylinder 31- above the piston 33 to 'continuously maintain hydraulic-fluid above the piston 33, notwithstanding the direction of movement thereof. When the piston 2 is pneumatically moved downwardly, the piston 33 is moved downwardly through the piston rod 34. As the piston 33 moves downwardly, hydraulic fluid 'from the reservoir cylinder 32 is forced by the compressed air above the hydraulic fluid in the reservoir cylinder '32 into the hydraulic cylinder 3| above-the piston 33 as' described. The hydraulic fluid in the 'cylinder'3l below the piston 33 is forced by-the piston 33 through the port 36,'the

valve 31 and the conduit 38 into the reservoir cylinder 32. The valve 31 is adjusted to provide a flow of the hydraulic fluid therethrough which will'provide a desired rate of movement of the piston 33 and thus the piston 2. At the same time, hydraulic fluid is prevented from passing through the annular space 35, the port 42, the'conduits' 39 and 4|, and the ports 44 and 43 to the reservoir cylinder 32 by the check valve 40. Upon the return movement of the piston 33 following its reaching its lowermost position, hydraulic fluid above the piston 33 is returned through the port 5|, the'conduit 48 and the ports 49 and 53 to the reservoir cylinder 32. At the same time, hydraulic fluid from the reservoir cylinder 32 is conducted into the'hydraulic cylinder 3|, beneath the piston 33, by the ports 43 and 44, the conduit at a slow feeding rate due to the restricted orifice provided by the valve 31. As the member 2 is connected 'to the piston 33 by the connecting rod 34', the rate of movement of the piston 2 will be limited by the rate of movement of the piston-33.

During the operation of the feed controldisclosed in Figs. 3 through 6, air bubbles are prevented from gettinginto the hydraulic fluid not only because of the packing rings 13 and I5. and

lar in construction and function to the form dis- .closed' in Figs. 1 and 2, except that whereas the form disclosed in Figs. 1 and 2 is for vertical operation," the form disclosed in Figs. 7 and 8 is for horizontal operation. The pneumatic cylinder l, the piston 2 therein, the piston rod 3 controlled thereby, the'piston 5, and the piston rod 4 connecting the piston 5 and the piston 2, together liflcloses the outer ends of the hydraulic chamber 6 and the reservoir cylinder 59. Arranged in the wall of the hydraulic chamber 6 adjacent the cap 60 is a port 6| providing .a communication between the hydraulic chamber 6. and the reservoir cylinder 59. For insuring that. the hydraulic chamber 6 is maintained filled with hydraulic fluid, the cap 60 is provided with ports 62 and 63 with whicha suitable connection with a source'of compressed air not shown is provided. The compressed airon the top surface of the hydraulic fluidin thereservoir cylinder 59 urges the hydraulic fluid upwardly through the port 6| into the hydraulic chamber 6. It is to be understood that there is sufficient hydraulic fluid'in the sys tem and in ,the reservoir cylinder 59 so that the level of the hydraulic fluid in the reservoir cylinder 53 will never fall below the level of the port 6|.

For lby-passing hydraulic fluid between the cylindricarportion "l of the hydraulic chamber 6 during slow feeding movement, there is provided in theendmember I I, a port 64 to which. is connected a valve 65, which in turn is connected by a conduit 66 to the lower portion of the reservoir cylinder 59. From the description ofthe previously described forms-of the invention, it will floeapparent that the valve may be ad-- justed toprovide a restricted orifice of such a size as'to providethe desired rate of feeding movement of the piston 5 and consequently the piston 2. Alsogitwill be understood that the communicationbetween the'conduit 63 and the reservoir cylinder 59 should be at some point below the minimum level of the hydraulic fluid therein.

; Still another form of the invention is disclosed in Figs. 9 through 12. This form of the invention issimilarto the form disclosed in Figs. 3 through 6; thedifference being that whereas the form of vthe invention disclosed in Figs. 3 through 6 is for vertical operation, the form of the invention disclosed in Figs. 8 through'12 is for horizontal operation. I

.The construction of the form of the invention disclosed in Figs. 9 through 12 is almost identical the vent "3 as described in connection with the form of the invention disclosed in Figs'l and 2,

but also because the maintenance of hydraulic fluid above the piston 33-at all times prevents the passage of air past the piston 33 into the hydraulic fluid which would occur if air were permitted directly above the piston 33. Also, the connection between the reservoir cylinder 32 and the valve 31 will be below the level 55 of the hydraulic fluid at all times, thereby preventing the drawing of air into thehydraulic fluid duringreturn movement of the piston 33.

with that disclosed in Figs. 3 through 6, as will be observed by reference to the like referencecharacters. However, since the reservoir cylinder 32 is in horizontalposition in the latter form of the invention, it will be'necessary that the com- ,munication between the by-passing valve 31 and the reservoir cylinder 32 be made at some point below the minimum level of the hydraulic fluid therein. Accordingly, there is provided aconduit provide a communication, as in the, case of the disclosure. of Fig- 4, between a suitable source. of

compressed air and. the reservoir cylinder 3.2,.

The passage through which the hydraulic fluid is driven. by the compressed. air from the reservoir I cylinder 32 to the hydraulic cylinder 3|. is provided by ports 10, H and 12 in the cap 52 as shown inv Fig; 12.. The port 1-0 communicates directly with the reservoir cylinder 32, the port 12' communicates directly with the hydraulic cylinder 3| and the port H connects the ports and 12. As shown. inFig. 12, the port H is provided by drilling in from one side of the cap 52 and the open end. of the bore thus formed is' closed with a plug 13..

It will be understood that the operation of the form of the invention disclosed in Figs; 9 through 12; is the same as the operation of the form of the invention disclosed in Figs. 3' through 6-. From the foregoing specification it will be ap-. parent that the advantages for each form of the invention are present in each other form of the invention. Furthermore, it will be clear that I have produced a hydraulic feed control which has minimized the possibility of entrance of air bubbles into the hydraulic fluid and further has minimized the effect of air bubbles that do accidentally get into the hydraulic fluid, in that. they are. placed under high compression. The high compression reduces the size of the air bubbles, and therefore reduces to a minimum the jump in feeding occurring as the air bubbles pass through the: restricted orifice.

In the forms of the invention wherein a reservoir is employed for maintaining suflicient hydraulic fluid on both sides of the piston in all positions thereof to cover the same, it will be evident that instead of employing air under pressure to direct the hydraulic fluid from the reservoir to .the hydraulic cylinder, the parts may be arranged, as shown, to cause the hydraulic fluid to flow from the reservoir by gravity into the hydraulic cylinder. Should it become necessary to place the feed control in any position other than illustrated, it will be necessary .to place all fluid ports entering cylinders 6 or3l below fluid level for obvious reasons. The enlarged chamber portion 8 of the construction of Fig. 1 is in efiect a form of such a reservoir. Accordingly any reference in the claims to yieldingly urging hydraulic fluid from the reservoir is intended to broadly include urging by gravity as well as compressed air. In addition it will be understood that other means for yieldably urging the hydraulic fluid from the reservoir is included.

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

l. A device of the character described for controlling the rate of movement of a resiliently moved member, comprising a hydraulic cylinder,

a cooperating piston arranged for movement in said cylinder, a rigid connection between said piston and said'member, whereby said member moves said piston, a jacket about said cylinder defining therewith a reservoir for hydraulic fluid, hydraulic fluid passages between said cylinder and reservoir for maintaining hydraulic fluid on both sides of said piston at all positions thereof and hydrau lic fluid passages for controlling the rate of movement of said piston and through itthe rate of movement of said member, and means for directihg the pressure of compressed air on the hydraulic fluid in said reservoir to force the hydraulic fluid into said cylinder and to maintain the hydraulic fluid in said cylinder under pres- 0 the rate of movement of said piston and throughsureto reduce the size of air or the like bubbles therein. 1

2. A device of the character described for controlling the rate of movement of a resiliently moved: member, comprising a-hydraulic cylinder,

-acooperating piston arranged for movement in reservoir for permitting. the escape of hydraulic fluid moved by said piston from said cylinder, at a predetermined rate for-controlling the rate of movement of said piston and through it the rate of movement of said member, means to provide from said reservoir 'suflicient hydraulic fluidon both sides of said piston in all positions thereof to cover the same, and means-for directing the pressure of compressed air on the hydraulic fluid in said reservoir to force the hydraulic fluid into said cylinder and to maintain the hydraulic fluid in said cylinder under pressure to reduce the size of air or the like bubbles therein.

3. A device of the character described for controlling the rate of movement of a resiliently moved member, comprising a hydraulic cylinder, a cooperating piston arranged for movement in said. cylinder, a rigid connection between said piston and said member, whereby said member moves said piston, a hydraulic fluid reservoir, a fluid connection between said reservoir and one end of'said' cylinder, means for connecting a source of compressed air to saidreservoir for urging hydraulic fluid from said reservoir through said fluid connection into said cylinder, and means for permitting the escape of hydraulic fluid from the other end of said cylinder as said piston is moved toward said other end, whereby 4. A device of the character described for con-- trolling the rate of movement of a resiliently moved member, comprising a hydraulic cylinder, a cooperating piston arranged for movement in said cylinder, a rigid connection between said piston and said member, whereby said member moves said piston, an annular hydraulic fluid reservoir disposed about said cylinder, a fluid connection between said reservoir and one end of said cylinder, means for connecting a source of compressed. air to the upper portion of said reservoir for urging hydraulic fluid from said reservoir through said fluid connection into said cylinder; and means for permitting the escape of hydraulic fluid from the other end of said cylinder at a predetermined rate: and for returning hydraulic fluid to said other end of said cylinder as said piston is moved, whereby the rate of movement of said piston and through it the rate of movement of said member, is controlled by the rate of escape and return. of said hydraulic fluid. 1

5. A device of the character described for controlling the rate of movement of a resiliently moved member, comprising a hydraulic cylinder, a cooperating piston arranged for movement in said cylinder, a rigid connection between said piston and said member; whereby said-member moves said piston, an annular hydraulic fluid reservoir disposed about said cylinder, a fluid connection between said-reservoir and one end of said cylinder, means connecting a source of compressed air to the upper portion of said reservoir for urging hydraulic fluid from said reservoir through said fluid connection into said cylinder, a fluid connection between the other end of said cylinder and said reservoir, said fluid connection having a restricted orifice therein to limit the rate of flow of fluid therethrougn'and another conduit connection between said last named end of said cylinder and said reservoir, said last named conduit connection having a check valve therein, whereby when said piston moves toward said last named end of said cylinder, hydraulic fluid flows through said restricted orifice into said reservoir and when said piston moves in the opposite direction, hydraulic fluid flows from said reservoir through said check valve into said cylinder, the rate of movement of said piston in the first direction being slow and in the second direction being rapid.

6. A device of the character described for controlling the rate of 'movement of a resiliently moved member, comprising a hydraulic chamber, said chamber having at one end thereof an active cylindrical portion and at the other end thereof an enlarged inactive portion, a piston arranged for movement in said chamber from said enlarged portion into said cylindrical portion and reverse, a rigid connection between said piston and said member, whereby said member moves said piston, an annular hydraulic fluid reservoir about said cylinder, the outside of said cylinder defining the inner wall of said reservoir, a fluid connection between said reservoir and said enlarged portion of said chamber for maintainin hydraulic fluid on both sides of said piston at all positions thereof, means for yieldingly urging hydraulic fluid from said reservoir through said fluid connection into said chamber, and means for permitting the escape of hydraulic fluid from in front of said piston as it moves in said cylindrical portion, said escaping means having a restricted orifice whereby said piston may move through said enlarged portion of said chamber connections effective during operation of said device between said reservoir and said'cylinder for maintaining hydraulic fluid on both sides of said piston in all positions thereof, and means for directing the pressure of compressed air on the hydraulic fluid in said reservoir to force the hydraulic fluid into said cylinder and to maintain the hydraulic fluid in said cylinder under pressure to reduce the size of air or the like bubbles therein, and hydraulic fluid passages for controlling the rate of said piston and through it the rate of movement of said member.

LOYD' A. WARD.