US2520129A

US2520129A - Lubricating system

Info

Publication number: US2520129A
Application number: US484806A
Authority: US
Inventors: Albert H Dall; Martellotti Mario
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-04-28
Filing date: 1943-04-28
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Aug. 29, 1950 A. H. DALL ETAL LUBRICATING SYSTEM 4 sheets-snelst 1 y Filed April 28, 1945 Alill wh @Y bwl wwf lm. uw.. wh W 5R. z UVW HN ll I I l l l l l ll m E nmml. Fl. www @M .www om, L. N D l @l %mh *am Mn. www wm, www ma lm w A wk l hmww. www lll l .ll lllll ll n. l .HVT l 5 m L lLl l U @wwf law w T mm Il wyw 0mm. .om wl' mmm w mw nl N NH w SJ QN m AN. |.illllllll` El MN WN www NNNNH Aug. 29, 1950 A. H. DALL Erm.

LUBRICATING SYSTEM 4 Sheets-Sheet 2 Filed April 28, 1945 Aug. 29, 1950 A. H. DALL ErAL 2,520,129

l LUBRICATING SYSTEM Filed April 28, 1943 4 Sheets-Sheet 3 IIa' a4 INVENTOR.

Aug. 29, 1950 A. H. DALL Erm.

LUBRICATING SYSTEM 4 Sheets-Sheet 4 Filed April 2s, 194:5

1 s...| lllllllll lLJ Patented Aug. 29, 1950 LUBRICATING SYS TEM Albert H. Dall, Silverton, and `Maro Martellotti, Cincinnati, Ohio Application April 28, 1943, SerialgNo. 484,806

l2 Claims. l

This invention relates to lubrication, and. with regard to certain features thereof., to lubrication in which the film of lubricant is yautomatically maintained.

One .ci .the objects of this invention is to provide practical apparatus for the above purpose of simple construction and eiicient and dependable action. vAnother Vobject is to provide lubricating .anoaratus adapted to maintain effective action under varying conditions ,of use. Another object is to provide apparatus of the above nature adapted to maintain a lubricant film on various forms and types of bearing surfaces. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, .arrangements of parts, and in the several steps and relation and Order of each of the same to one or more of the others, all as will be illustratively described herein, and the .scope of the Yapplication of which will be indicated in the iollowing claims.

In the accompanying drawings in which is shown one of the various possible embodiments of the mechanical features of this invention:

Figure 1 is a top plan of a grinding machine;

Figure 2 is a diagrammatic plan .showing the relation of various ,parts for 'handling lthe lubricant;

`Figure 3 is a sectional elevation .taken along the 'line 3-3 o f Figure Y2 .showing the parts structurally rather than lin diagrammatic form;

Figure 14 is a similar section taken along the line 4-4 .of Figure 2; and,

Figure 5 is a similar section taken along the line 5--5 of Figure 2.

Similar reference characters refer to similar parts throughout the several views ofthe .drawings.

`Referring now to 'Figure 1 of the drawings, the rinvention vis shown embodied `in a grinding machine in which `the main bed is indicated at I0, this bed being broken away as indicated at II' and being of such total length as to permit any desired travel of the table I2 mounted thereon.

The bed or Support for the grinding head is indicated at I3, extending, as usual, at right angles to the main table and -having ,the head I4 mounted to reciprocate, as indicated by the double arrow, traveling in this direction under either manual vor automatic control in the usual manner. This head supports the grinding wheel I5 driven in the usual manner by a suitable electric motor on the `grinding head.

Referring to the Atable i2, it is provided with the headstock lL6 mounted onone .end thereof and at the l,opposite end with the tailstock ,or footstock il which is .adjustable lengthwise of the table by the usual mechanism. Headstock .and footstock are respectively provided with the .centers I8 `and I9, and the work, indicated at 20, is rotated by the motor 2l geared to drive any suitable form of Aconnection from its face plate 22.

The main table I2 travels or reciprocates along the -bed under either automatic .or manual drive connected b y mechanism of any of the well Aknown .suitable types.

The table I2 rests, as shown in Figure 3 of the drawings, on the V-shaped way having the surface-s 23 .and '24 between which the down.- wardly `projecting portion '25 of the table fits. These parts extend lengthwise of the machine .throughout the length of the table and through.- out .such portion of the length of the bed as will afford to the table the maximum desired travel. On the other side of theI machine, commonly called the front side, the bed is `provided with a flat Yhorizontal surface 2B on which the bearing portion 21 of the table rests. These ,coacting .surfaces also extend throughout the length of the table and substantially throughout the length of 'the bed.

The supporting bed for the grinding head -III is provided with ways forming the dat bearing surface .2.8 and the surfaces 29 disposed vto form an inverted V. Respectively coacting with these bearing surfaces are those at the bottom oi .the parts '3D and .3.I through which the grinding head is carried, all `as shown in Figure 5 of the drawings.

As ,casting light on `the features about to -.be described, itis to be noted that the load ,distribution along a member such as table I2 is inherently irregular; that is, the weight imposed on the bearings at one part, as, for example, the headstock, is quite diierent from that imposed at ,another longitudinally spaced location as under the unsupported .center of the work. This lack of uniformity, moreover, varies widely under different conditions and the resultant load, furthermore, varies in direction, these variables depending, for example.,v on the connection and distribution of the work, the position of the iootstock, and the .side thrust of the grinding wheel or other tool. If it were attempted merely to use a lubricating system of high pressure in order to reduce friction, such pressure, if adequate at, for example, the headstock, would tend to be excessive at certain other parts and even tend to bend the table. This bending action gives rise, among other objectionable features, to a tendency of the ends of the table to settle, and, by offering heavy pressure on extremely small surfaces, break through the lubricant film and scrape metal-to-metal along the surface of the bed.

It is also to be noted that in many lubricating arrangements of the ordinary type the effort to meet the problems presented places restrictions on the materials to be used in order to avoid scoring the galling of the surfaces. Furthermore, the power requirements in such arrangements, both for working and idle movements, are considerable and often special auxiliary devices are required in connection with the manual actuation of heavily loaded slides.

One other point to be noted is that, with a reciprocating part such as the table I2, it must, of course, come to a standstill at each end of its travel or stroke and to start its return trip must overcome static friction as well as inertia, the static friction being normally substantially in excess of the kinetic friction encountered during movement. There is, accordingly, a tendency to deviation from a smooth reversal due to this action and a problem introduced which is not found in a bearing in which the parts are in continuous relative movement.

Turning to the means whereby the problems thus introduced are solved herein, reference is made to Figure 2 which might be termed a hydraulic diagram. It will be understood'that the term hydraulic is broadly used, and it may also be noted that the term reciprocating is used throughout in a broad sense to denote any nonN rotary travel and to include movement which might technically be called oscillating. There is indicated at 32 an electric motor driving a lubricant pump 33 which draws lubricant as by the pipe 36 from a sump which extends throughout the lower portion of the bed I6. The discharge from this pump is of relatively high pressure and of a volume ample for the purposes hereinafter described.

At 35 is indicated a form of pressure regulator which is an adjustable relief valve having a spring-pressed part 36 controlling a by-pass 37 which returns to the sump. This relief valve having been set at a suitable pressure, as, for example, 100 lbs. to the square inch, will maintain that as a maximum pressure of its output, and its volume is such that there is normally a continuous overflow through the by-pass 3l'. At the discharge end of this pressure regulator a conduit 38 is provided with a branch ."i which supplies a lubricating unit 4G hereinafter described in detail.

The main flow from the pump, after passing the branch 39, travels through an adjustable reducing valve l by which the pressure is subu stantially reduced. From this valve conduit 42 is branched at G3 to lead to two discharge openings 44 and S5 in the bed. These discharge ports are both arranged opposite a groove 4B formed in the under surface of the table as shown in Figure 3. This groove eX'Lends substantially throughout the length of the table, as indicated in Figure 2, and is connected, preferably at a plurality oflongitudinally spaced points, by the short pipes 4l, 43, and d with a conduit 50 connected to a conduit 50a leading to a high pressure pump 5l driven by a motor i preferably mounted on the end of the table. The high pressure lubricant from the pump 5i is carried by a conduit 52 throughout the length of the table substantially parallel with the conduit 59, as shown in Figure 2 of the drawings. A relief valve having a spring pressed part 8| is connected to the high pressure conduit 52 by a conduit 82; the discharge from the relief valve is carried to the sump by way of line 83.

Spaced along the table are a number of lubricating units, here shown as siX, on the main table. As these are substantially identical in construction and action, one only will be described. From pipe 52 three branches lead through

pressure reducing devices

53, 54, and 55. These devices may be considered as coils of any desired length and each having a, passage therethrough of very small cross section. Preferably the physical construction of th'ese pressure reducing devices, as shown in Figure 3, take the form of a plug having a spiral thread throughout the entire outer surface through which the lubricant flows.

The discharge from pipe 52 travels through one of these devices and its pressure with a normal rate of now is thereby reduced. The lubricant of reduced pressure flows through an outlet 56 and a passage 51 into a pocket or recess 58 formed in the under surface of the bearing portion 21. This recess or pocket is preferably elongated in the direction of the length of the table, as indicated in Figure 2, and the sole discharge of lubricant therefrom escapes through the films formed between the bearing surfaces of the adjacent portion of the bearing, as will be later eX- plained.

The escaping lubricant travels at one side over the edge of the bearing surface of the bed into a trough 59 (see Figure 3) from which it is discharged as through the pipe GO down into ie sump formed by the bottom of the bed or frame of the machine. The lubricant escaping toward the opposite side is picked up by a groove Si formed in the table and extending parallel to and substantially coextensive in length with the groove 45. This drainage groove 6l is connected by any suitable passage or conduit (diagrammatically indicated at SI2) with the groove 52 on the opposite side of the inlet groove 4t, and these drainage groovesserve to collect lubricant fiowing in their direction from the adjacent films and discharge it into the sump as through the pipe 63. Any excess lubricant flowing toward the inner or right-hand edge of the bearing as viewed in Figure 3 is gathered by the trough 64 and discharged into the sump by the c rain pipe 65.

Considering the action of the lubricating parts thus far described, assuming that the lubricating system is rst started up with the bearing surfaces in metal-to-metal contact, the lubricant flows into the various recesses, such as pocket 58. The escape from the pocket being at this stage out off, the pressure therein naturally rises until it reaches a point sufficient to raise the table and cause a slight separation of the adjacent bearing surfaces on the table and bed. This separation affords an escape of the lubricant from the pocket, and, due to its restricted cross section, this crevice forms what may be considered a hydraulic resistance, just as is the constricted passage through the device 53. This crevice between the bearing surfaces increases in width due to the lift of the lubricant on the upper surface of the pocket and, acting through the film, on the under surface of the table. When the hydraulic resistance of the outflowing lubricant through the films equals that of the corresponding device 53 at the inlet to the pocket, then the .pressure of Ythe supply line.

'.foumow through thenlmiis .lequal'stozthe innova .to the pocket.

at the 'point l'cn-der construction, there is a tendency to constriction of 'the imm through :an

Vcirtremely 'minute downward movement of the r4table toward :the bed. .This tendszto :choke oir lthe escape of `lubricant and the pressure vbuilds. lup

.inthe pocket. lOi course, if .the fescapewerez'com- Epletely closed, as is notthe case, then the `pressure f "in fthe pocket would zincrease :until vit'sequaled the .'However, teven la fsiight constriction of the outilowing film results 'in afsubstantial excess of pressure, which increase continues until the additional load isI 'of resistance'sizes so that they will balance the computed .load imposed on the portion of `the bearing at which `the .particular pocket vis located. With such balance there isa continuous @flow of lubricant into and out of the pockets, the `new out of the .pocket being .in the V.iorm of .a :pressure nlm of thickness .suilcient .to guard @against any chance .of Va metal-to-metal contact.

All of the foregoing .actions occur .instantane-` ously on `Va tendency to variation in .the vnlm thickness, and the remedyis applied simultaneously with the occurrence of variation .in effective load. Ilin this manner the lm thickness is `maintainsd .approximately constant, and anyfff vchance of rupture of the lmis precluded. The '.movingpart, .the table, thus travels on .alubricant surface and lits friction is reduced toa minimum.

At the .opposite side of the bed the bearing comprises two pockets 56 and Gi, and, although vin the diagrammatic view Figure 2 'the .supply 'of .these pockets is shown for clarity as having vseparate .connections with'the high pressure lline 52, they are physical structure preferably joined, as indicated in Figure 3. The devices 5A. vand 55 lead through suitable passages to the recesses .or .pockets 6o and G7, as shown, and have the same automatic action as described with reference to the similar pocket 58 on the viorw'ard side of the Ymachine The .discharge "from the Afilms is 'taken in the troughs 68 "and 59 connected, ias by 'the piping 68a 'and Elia shown, with 'the 'sum-p. This piping also takes drainage from the .groove at the bottom of .the V.

With respect to the .pocket 8S, it is to be noted thatitextends transversely not .on-ly to the line of .downward .pressure Vfrom the table of the main .machine but also .to the resultant of thelateral forces brought about by the operation of the vgrinding wheel. Thus any variation in direction of theresultant of the lateral forces due to the grinding Wheel .or other device is automatically resisted. and compensated `for .just as is .the downward .pressure on the bearing twhich extends along the -front of the machine.

Referring to the unit 4l) shown in ,Figure 5 7of .thedrawings it is .believed that detailed description will be unnecessary. The pressure reducing devices are diagrammatically indicated .as coils Arather than in the .preferred physical .iormof helically grooved plugs, as shown in Figfure The two devices onY the left-hand side lead respectively to pockets TE! and 1| diagrammatically indicated in Figure 2, the lpocket lil .in its relation to the bearing being shown in Figure P5. thefother side of the funitth'e four devices aleadfrespectivelyftothe pair "orf pockets '|22and .13 andthe-simiar pockets spaced vtherefrom in the -.direction of travel of 'the grinder yhead1 :The supply conduit 39zis preferably of ilexible fiform, as "indicated vin :Figure 5, to permit `full travel ofthe grinder head, and this conduit leads :to ftnere'ceptable d4 .from which the various :reducing units are supplied.

Considering .broadly the action .by which I.the various problems encountered are solved, it may flrstfbe noted .that the lubricant is injected at various vportions of the bearings in a manner 'to create Vpressures suited to the particular load on `that yarea .byproper'selection'of'resistance fvalues. Furthermore, the lifting pressure for any )area fisautoinatically Vvaried to meet any variations :of load at that area independently 'of'what is occurring at anyother portion of the bearings. These pressures :are not only 'varied ybut are :brought liuto .effect :such 'direction-s as Ato .meet variations in direction :as well as 4amount of the-resultant Iload in the Aadiac'ent neighborhood. It 'is also to benoted that the pressure in the 'system as `la Whole is controlled to .meet the particular conditionsas theflubricant travels from the sump throughout "its enti-re trip back to the sump. =In this particular machine the pressure is rst raised and thenfsupplied with 'ample volume but vat a chosen maximum limit. In this Icondition :it vsupplies the grinder head. The pressure 'is then reduced to be suitable for transmission through the .pick-up arrangement comprising ports l44 'and 45 tothe ,groove doin the relatively 'movable main table., and it is transferred .atra number of points to the main supply conduit 5t .so as 'to assure ample feed lto that lconduit and avoid :any chance in Vfall of pressure by .protracted travel through the groove or slot `46. rhe pressure is then raised 'on the table Vand is supplied .to vthe various .units as herein described.

It will accordingly be seen that there ,is :provided apparatus whereby the objects of this .invention area'ttained in an essentially practical manner well .adapted to meet the hardest A'and most varying conditions of use.

As many possible vembodiments may be made Iof the mechanical features of the above invention, and as "the 1art herein described lmiffht be varied in various parts, Vall without departing from the scope :of the invention, it is to :be understoodfthatall matter hereinabove set forth, or shown in the accompanying drawings, is to Abe interpreted as -illustrative and not `in a limiting sense.

We claim:

i. In a lubricating system, in combination, a vmachine tool comprisinga bed and a table mov- .able Yalong the same, means adapted to supply liouid at relatively .low pressure, said table .and bed having a connection comprising a groove in one oi vthe same inthe direction of movement of the table and a passage in the other communieating with .said groove in all positions .of .the '.table, ra lubricant pump ,mounted on said table, ymeans leading said low pressure liquid through said .connection to said pump, and means leading liquid from said ,pump to the bearing suryfaces between said table and bed.

2. Ina lubricating system, in combination, a machine tool comprising a bed and a table adapted to travel along the same, said table having a .longitudinal groove in its under surface connesting with a conduit on said b'ed adapted to lead lubricant to said 'groove in all positions of the table, and said table having lubricant-receiving recesses in its bearing surface on the bed, means adapted to supply lubricant to said recesses from said groove through conduits of restricted cross section, the sole escape from said recesses being through lubricant illms between the adjacent bearing surfaces, and means comprising grooves extending longitudinally along the bed spaced from said recesses and adapted to collect lubricant as it is discharged from the bearing through said films.

3. In a lubricating system, in combination, a machine tool including a bed and a table, said table being movable along said bed on way bearing surfaces, means to supply liquid at relatively low pressure, said table and bed having a connection comprising a groove in one of the same in the direction of movement of the table and a passage in the other communicating with said groove in all positions of the table, a liquid pump mounted on said table, means leading said low pressure liquid through said connection to said pump, means forming a plurality of recesses in said way bearing surfaces, and means connecting said pump to said recesses, said pump constantly supplying liquid to each of said recesses under suicient pressure to lift the portion of the table positioned above each recess.

4. In a lubricating system, in combination, a supporting member, an elongated slide member, said members having opposed load-supporting bearing surfaces and said slide member being mounted for movement with respect to said supporting member on said bearing surfaces, at least one of said bearing surfaces having a plurality of recesses formed therein and spaced from the edges of said surface, said recesses being longitudinally spaced from each other in the direction of said movement, and a separate conduit for each recess containing a ow restriction through which fluid is pumped continuously to each recess under table lifting pressure controlled by the separation of said surfaces to create and maintain a table supporting illm between said surfaces under suflicient pressure to separate said bearing surfaces, whereby there is a continuous flow of fluid between said bearing surfaces.

5. In a lubricating system, in combination, a supporting member having a flat load-supporting bearing surface, a work supporting member having a flat load-supporting bearing surface, said work supporting member being mounted for movement with respect to said first-mentioned member on said bearing surfaces, said work supporting member having a plurality of recesses formed in its bearing surface and spaced from the edges of said surface, said recesses being longitudinally spaced from each other in the direction of said movement, and separate conduits for each recess, each conduit containing a flow restriction and being connected at one end to a recess and to a source of fluid under pressure at the other end, said source of fluid under pressure being operable to continuously supply fluid to each recess through said conduits under work supporting pressure controlled by the separation of said surfaces to create and maintain a work supporting film under pressure to separate said bearing surfaces, whereby there is a continuous flow of iluid between said bearing surfaces.

l 6. In a lubricating system, in combination, a supporting member having a ilat load-supporting bearing surface, a avork supporting member having a rlat load-supporting bearing surface,`

said work supporting member being mounted for movement with respect to said first-mentioned member on said bearing surfaces, said work supporting member having a plurality of recesses formed in its bearing surface and spaced from the edges of said surface, said recesses being spaced from each other in the direction of said movement, a pump, and a separate conduit for each recess containing a flow resistance and connecting the pressure side of Said pump to each recess, said lpump being operable to continuously supply iluid through said conduits to each recess under work supporting pressure controlled lby the separation of said surfaces to create and maintain a work supporting film under pressure to separate said bearing surfaces, whereby there is a continuous flow of fluid between said bearing surfaces.

7. In a lubricating system for a machine tool, in combination, a bed, a table, said bed and table having opposed load-supporting way bearing surfaces, said table being mounted for longitudinal movement with respect to said bed on said way bearing surfaces, at least one of said bearing surfaces having a plurality of recesses formed therein, said recesses being spaced from the edges of the bearing surfaces in which they are formed and being longitudinally spaced with respect to each other in the direction of said movement. the principal path for escape of fluid from each recess being between said bearing surfaces, and a separate vconduit for each recess containing a flow restriction through 'which fluid is pumped continuously to each recess under table lifting pressure controlled by the separation of said surfaces to create and maintain a table supporting film between said surfaces under sufficient pressure to separate said bearing surfaces, whereby there is a continuous ilow of fluid between said bearing surfaces. l

8. In a lubricating system, in combination, a supporting member, an elongated slide member, said members having opposed load-supporting bearing surfaces and said slide member being mounted for movement with respect to said supporting member on said bearing surfaces, at least one of said bearing surfaces having a plurality of recesses formed therein and spaced from the edges of said bearing surface, said recesses being longitudinally spaced from each other in the direction of said movement, and a. separate conduit for each recess containing a hydraulic resistance and each connecting a recess to a source of liquid under pressure. the sole path of escape of said liquid from each recess being between said hearing surfaces thereby forming a hydraulic resistance to flow out of each recess, said source of liquid under pressure being operable to continuously supply liquid through said conduits to each recess under slide lifting pressure controlled by said second-mentioned hydraulic resistances to create and maintain a slide supporting lm under pressure vto separate said bearing surfaces, whereby there is a continuous flow of iluid between said bearing surfaces.

9. In a lubricating system for a machine tool, in combination, a bed, a table, said bed and table having opposed load-supporting way bearing surfaces, said table being mounted for longitudinal movement with respect to said bed on said way bearing surfaces, at least one of said bearing surfaces having a plurality of recesses formed therein and spaced from the edges of said surface, said recesses being longitudinally spaced from each other in the direction oi' said movement, and a separate conduit `for each recess containing a hydraulic resistance and each connecting a recess to a source of liquid under pressure, the sole path for escape of said liquid from each recess being between said bearing surfaces and forming a hydraulic resistance to i'iow out of each recess, said source of liquid under pressure being operable to continuously supply liquid through said conduits to each recess under table lifting pressure controlled by the separation of said surfaces to create and maintain a table supporting film under pressure to separate said way bearing surfaces, whereby there is a continuous flow of fluid between said bearing surfaces.

lo. in a lubricating system for a machine tool, in combination, a bed, a table, said bed and table having opposed pairs of load-supporting way bearing surfaces, said table being mounted for longitudinal movement with respect to said bed on said way bearing surfaces, said table being of uneven weight throughout its length and being long in comparison with its thickness with a tendency to bend vertically, said table way bearing surfaces each having a plurality of recesses formed therein, said recesses being spaced from the edges of said table way bearing surfaces and being longitudinally spaced with respect to each other in the direction of said movement oi said table, the sole path for escape of fluid from each recess being between said bearing surfaces, and a separate conduit for each recess contain ing a flow restriction and connecting the pressure side of a pump to each recess, said pump being operable to continuously supply fluid through said conduits to each recess under table lifting pressure controlled by the separation of said surfaces to create and maintain a table sup porting film under pressure to separate said bearing surfaces at all points, said pressure lifting the weight or any portion of the table plus any additional load that might be placed thereon when the machine is in use, whereby there is a continuous flow of fluid between said bearing surfaces.

11. In a lubricating system for a machine tool, in combination, a bed, a table, said bed and table having opposed load-supporting flat way a bearing surfaces on said table having a plurality of recesses formed therein, said recesses being spaced from the edges of the bearing surfaces in which they are positioned and being longitudinally spaced with respect to each other in the direction of movement of said table, 'the sole path for escape of liquid from each recess being between said bearing surfaces and forming a hydraulic resistance to flow of liquid from each recess, and a separate conduit for each recess containing a hydraulic resistance through which fluid is pumped continuously to each recess under table lifting pressure controlled by the separation ol said surfaces to create and maintain a table supporting lm between said bearing suriaces under pressure to separate said bearing surfaces, whereby there is a continuous ilow of fluid between said bearing surfaces.

i2. In a lubricating system, in combination, a supporting member, an elongated slide member, said members having opposed load-supporting bearirrT surfaces and said slide member being mounted for movement with respect to said supporting member on said bearing surfaces, at least one of said bearing surfaces having a plurality of recesses formed therein and spaced from the of said surface, said recesses being lond, 'ually spaced from each other in the direction of said movement, a pump, a relief valve connected to the pressure side of said pump, and "te conduit connecting each recess to the press te side of said pump, a hydraulic resistance ositioned in each conduit, said pump bfng operable to continuously supply liquid g film under pressure to separate said be. g surfaces, whereby there is a continuous flow of fluid between said bearing surfaces.

ALBERT H. DALL.

MARIO MARTELLOTTI.

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

UNITED STATES PATENTS Number Name Date 775,923 Holmes Nov. 29, 1904' 1,659,564 Baker May 25, 1928 1,771,301 Runder July 22, 1930 1,975,951. Kearns Oct. 9, 1934 2,921,066 Huxford Nov. l2, 1935 2,972,814 Haas Mar. 2, 1937 2,079,709 Archea May 11, 1937 2,146,983 Carter Dec. 20, 1938 2,351,620 Kocher June 20, 1944 FOREIGN PATENTS Number Country Date 244,539 Italy Jan. 30, 1926