US3053222A

US3053222A - Apparatus for the treatment of textile filamentary material

Info

Publication number: US3053222A
Application number: US766448A
Authority: US
Inventors: Brierley Edgar; Norris Alan Hedley
Original assignee: LEESONA HOLT Ltd
Current assignee: LEESONA HOLT Ltd
Priority date: 1958-07-22
Filing date: 1958-10-10
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11

Description

Sept. l1, 1962 E. BRIERLEY ETAL 3,053,222

APPARATUS FOR THE TREATMENT OF TEXTILE FILAMENTARY MATERIAL Filed 00T.. 10, 1958 5 Sheets-Sheet l INVENTQR Edgar-BrierleyAlan HANol-r'ls Bv AMW ATTORNEY APPARATUS FOR THE TREATMENT OF TEXTILE FILAMENTARY MATERIAL Filed OCT.. l0, 1958 Sept. 11, 1962 E. BRIERLEY ET AL 5 Sheets-Sheet 2 INVENTQR Edgar Erler-ley Alon H. Norm s ATTORNEY Sept. 11 1962 E. BRIERLEY ETAL 3,053,222

1YPPRTUS FOR THE TREATMENT OF TEXTILE F ILAMENTARY MATERIAL Filed 001... 150A, 1958 5 Sheets-Sheet 5 :INVENTOR ATTORNEY Sept. 11, 1962 E. BRIERLEY ET AL LAMENTARY MATERAL APPARATUS FOR THE TREATMENT OF TEXTILE F' Filed OOt. l0, 1958 5 Sheets-Sheet 4 mvENTQR EdgarBrierleyAlar/v H. Now-f5 BY A ATTORNEY Sept. 11, 1962 E. BRIERLEY ET AL 3,053,222

APPARATUS FOR THE TREATMENT OF TEXTILE FILAMENTARY MATERIAL Filed Oct. l0, 1958 5 Sheets-Sheet 5 M m h x li HHIHHNNH'HHMH- 11 3-1 5 TW: n 6\.m..n\ 6 11-1-.. I 8 --..UMU l 4. 1 f n lllllllllllllll Il f.

INVENTQR Edgar Brierley/Mcm H Norrls ATTORNEY Fci. 9.

United States Patent Oiiice Patented Sept. l 1, 1962 3,053,222 APPARATUS FR THE TREATMENT F TEXTILE FILAMENTARY MATERIAL Edgar Brierley, Bamford, Rochdale, and Alan Hedley Norris, Wardle, Rochdale, England, assignors, by mesue assignments, to Leesona Holt Limited, a corporation of Great Britain Filed 0ct. 10, 1958, Ser. No. 766,448 Claims priority, application Great Britain July 22, 1958 17 Claims. (Cl. 118-5) This invention refers to a method of and apparatus for the treatment of textile yarns or threads being wound on a winding machine and more particularly to the lubrication of said yarns or threads preparatory to subsequent processing and consists essentially in applying a liquid lubricant medium to the yarn or thread by utilising the capillary properties of a porous material to provide a moist film of the liquid lubricant medium on the surface of the porous material over which the thread is traversed whereby it becomes effectively lubricated, the lubrication being accomplished without materially adding tension to the yarn or thread.

The preferred lubricant is molten Wax, and any wax can be used irrespective of its hardness, it not being necessary to soften the wax by additives nor to prepare it in any form, thus providing the cheapest possible lubricant.

The present invention consists in a method of and apparatus for the applying of a liquid lubricant medium i.e., molten wax, to yarn or thread by utilising the capillary properties of a porous material to provide a moist film of the liquid lubricant medium on the surface of the porous material over which the yarn or thread is traversed whereby it is effectively lubricated; heating the solid wax to reduce it to the desired fluidity, maintaining the fluid lubricant at a desired constant temperature and also at a predetermined level of supply, whereby each yarn or thread from a multiplicity of spindles receives a uniform coating irrespective of any variation in room temperature; visual and/ or audible warning being given when the supply of lubricant medium falls below a pre- .determined level; and controlling the whole side of a winding machine from one point so ensuring even application of lubricant to the yarn or thread from spindle to spindle.

Apparatus for lubricating yarn or threads with molten lwax according to the method described include an insulated casing, a melting chamber located inside the casing and adapted to receive a supply of hard wax, the bottom of the melting chamber being formed as or furnished with a sieve; an electrical heating element located below the melting chamber and connected to a source of supply of electric current; a reservoir below the mel-ting chamber to receive molten wax flowing from the melting chamber through the sieve; an outlet branch from said reservoir; a tube coupled at one end to said outlet lbranch and extending along the whole length of one side of the winding machine to receive a supply of molten wax, the tube being furnished at its outer end with a T-piece formed with a bleed hole to permit escape of air from the tube; a multiplicity of cylindrical porous bushes intercalated in the tube line at spaced intervals in register with the spindles of the winding machine, there being a porous bush `for each spindle; an electrical heating element of the tape type, i.e., a Woven glass fibre tape embodying resistance wires, .connected to a source of supply of electric current, and

extending through the tube and porous bushes from end to end and being immersed in the molten wax flowing `through the tube and porous bushes; a thermostat in the electric circuit of the tape heating element, associated electric circuit of the heating element of the melting chamber; an over-riding thermostat located in the molten wax reservoir associated with a signal lamp also adapted to show a red light; a signal lamp in the electric circuit of the apparatus adapted to show an amber light, and descriptive plates located adjacent to said re-set button and signal lamps to indicate their function.

Advantageously the cylindrical porous bushes may be of porous iron with, for example, 30%-40% voids, or they may -be of suitable ceramic material permeable to wax, the pores being free enough to lift the molten wax by capillary action so that it penetrates the porous material to form a lm of molten wax on the exterior surface of the porous bush. Alternatively the bushes may Ibe of felt or be felt covered.

The apparatus works in combination with the usual ,tension devices, clearers, and thread guides of a winding machine, and is located between the clearer and the yarn traverse mechanism ofthe winding machine.

The operation of the lubricating apparatus is as follows: solid wax is placed in the melting chamber and the co-operating electric heating element is switched on, the amber signal light indicating that the apparatus is alive The heat from the electric element melts the wax in the melting chamber and molten wax flows through the sieve in the bottom of the melting chamber into the reservoir and thence through the outlet into the supply tube and porous bushes, air in the tube and bushes escaping through the bleed hole at the end of the tube.

Advantageously, in the initial starting up of the apparatus a supply of molten wax may be poured into the reservoir to expedite the operation while the solid wax in the melting chamber is being melted.

The current to the heating tape is switched on, the cooperating thermostat being set to the predetermined degree; the time switch controlling the wax melting heater is pre-set to the desired time. The molten wax lills the supply tube and porous bushes to a predetermined level and is maintained at the desired temperature by the heating tape located therein.

The molten wax in the cylindrical porous bushes is caused by capillary action to form an oily lm of molten wax `on the exterior surface of the porous bushes. Yarn being traversed over the oily surface of a porous bush absorbs molten wax and is etiiciently lubricated.

The amount of lubricant added to the yarn may be controlled in several ways, for example, by the temperature of the molten wax and the porous bush; by wrap of the yarn on the bush; or by traverse of the yarn over the bush.

The reciprocating motion of the traversing yarn guide laying the yarn from end to end of a package being wound causes the yarn travelling over the oily surface of the porous bush to traverse in correspondence to a lesser degree from end to end of the porous bush this lateral movement producing a side-ways action of the yarn over the oily surface of the porous bush and thereby ensuring an efficient lubrication of the yarn.

In the case of yarns of librous material, capillary action in the yarn itself would ensure eiiicient penetration of the molten wax.

Description will now be given of a practical embodiment of lubricating apparatus according to the invention applied to a textile winding machine, and its manner of operation, reference being made to the accompanying drawings, in which only so much of a winding machine is shown as is necessary for a clear understanding of the invention.

In the drawings:

FIG. 1 and FIG. la collectively illustrate a side elevation -of lubricating apparatus constructed according to the invention, the view being broken to shorten the figure;

FIG. 2 is an end elevation of FIG. l, looking in the direction indicated by the arrow A,

FIG. 3 is a plan of FIG. 2;

FIG. 4 is a sectional view drawn to a larger scale, taken through the line IV-IV of FIG. 1;

FIG. 5 is a fragmentary view, partly sectional showing the disposition of a porous bush in relation to a tension device and clearer of a textile winding machine, a yarn supply spindle also being shown diagrammatically;

FIG. 6 is a fragmentary sectional view, also drawn to a larger scale, of' the outer end of the lubricant supply tube;

FIG. 7 is a diagram of the electrical circuit of the apparatus;

FIG. 8 is a sectional view of a simple construction of apparatus according to a m'odied form of the invention;

FIG. 9 is a fragmentary plan of FIG. 8.

The same reference characters indicate corresponding parts in the several figures of the drawings.

Referring to the drawings 10 indicates a box-like outer casing made of sheet metal and located within the casing 10 is a further box-like casing 11 so supported in the outer casing 10 as to leave a space indicated at 12, which is lled with an insulating medium and serves to insulate the inner casing 11 from the outer casing 10 and so conserve heat in the casing 11 and keep the outer casing 10 cool.

Located in one corner of the inner casing 11 is a further box-like casing 13, hereafter referred to as the melting chamber 13, the upper part of which tits against the roof of the casing 10 in which there is formed an opening 14 normally closed by a cover 15 provided with a handle 16. In the lower part of the melting chamber 13 there is provided a casing 17 furnished with an electric heater element 18 connected to a source of supply of electric current. Also in the lower part of the melting chamber 13 is a sieve indicated at 19.

A space is left between the bottom of the melting chamber 13 and the iloor of the casing 11. The lower part of the casing 11 serves as a reservoir and will hereafter for convenience be referred to as the reservoir 20. In one corner of the reservoir 20 there is provided an outlet pipe 21. Coupled to the outlet pipe 2.1 by means of a clip 22 is a tube 23, hereafter referred to as the supply tube 23, in which is intercalated at spaced intervals a multiplicity of cylindrical porous bushes 24, the tube 23 and complemental porous bushes 24 extending along the whole of one side of a textile winding machine, and being supported in a semi-cylindrical trough 25 carried in bearers 26 on screw-threaded studs 27 screwing into extensions 28 of brackets 29 secured to the frame 30 of the winding machine, see FIGS. 2 and 5.

The porous bushes 2.4 are spaced along the tube 23 so that each bush 24 is in register with a spindle 31 of the winding machine, yarn, indicated at Y, being drawn from the spindle 31 through a tension device 32, and clearer 33 carried on the bracket 29, passing over the porous bush 24 to be wound on the winding roll 34, see FIG. 5, a wire guide 35 indicated in FIG. l, serving to direct the yarn Y to the porous bush 24. The tension device 32 and clearer 33 are of known types.

The tube 24 is furnished at its outer end with a nipple 36 to receive a T-piece 37, the lower arm of which. is provided with `a hollow screw-threaded plug 38 whlch is removable for the purpose of draining the tube 24. The upper arm 'of the T-piece 37 is provided with a screwthread plug 39 through which is drilled a small hole 40 to serve as a bleed hole for the escape of air from the tube 24 as the tube 24 fills up with molten wax.

Located in the reservoir 20 is a ball-float 41 the carnier arm 42' of which is pivoted at 43 on a plate 44 secured to the wall of the casing 11 and serving as a bracket.

The ball-float 41 is operatively associated with a microswitch 45 carried on the plate 44 in proximity to the carrier arm 42 of the ball-float 41, the micro-switch 45 being in the circuit of the electric heater 18. 46 indicates an electric heater of the known tape type, i.e., a woven glass fibre tape embodying resistance wires, the tape being immersed in the molten wax in the tube 23 and porous bushes 24.

The leads 47 of the heater tape 46 are connected to a thermostat 48 in the electric circuit of the heater 46. The bulb 49 of the thermostat 48 is immersed in the molten wax in the tube 23 and porous bushes 24, see FIG. 1. 5) indicates a time-delay switch of known type, 51 a signal lamp adapted to show a red light, and 52 a re-set button in the electric circuit of the heater 18 of the melting chamber 13. An over-riding thermostat 53 located in the reservoir 20 and in association with the red signal lamp 51 is intercalated in the electric circuit of the apparatus. A green light 54 indicates that the thermostat 48 is working. S5 indicates a signal lamp adapted to show an amber light, intercalated in the electric circuit of the apparatus. 56 indicates a descriptive plate describing the function of the re-set button 52; 57 a similar plate for the signal lamp 51; 58 a similar plate for the signal lamp 54 and the overriding thermostat 53, and 59 a similar plate for the signal lamp 55. 60 indicates a draining plug `in the floor of the reservoir 20.

In the working of the apparatus the operator removes the cover 15 and fills the melting chamber 13 with solid wax, indicated at S.W. in FIG. l, and replaces the cover 15; he then sets the thermostat 48 to the required setting. The time-switch 50 is pre-set to the predetermined time.

As previously stated a supply of molten wax is poured into the reservoir 20 to expedite the initial starting of the apparatus.

The electric heater 18 and the electric tape heater 46 are then switched on and the amber signal lamp is illuminated to show that the plant is alive.

The heater 18 causes the solid wax in the melting charnber 13 to melt yand the molten wax ilows through the sieve 19 into the reservoir 20 and via the outlet 21 through the supply tube 23 and porous bushes 24, air in the tube 23 and bushes 24 escaping to atmosphere through the bleed hole 40 and permitting a free flow of molten wax.

The level of the molten wax rises until it reaches a predetermined point as indicated at M.W. in FIG. l when the ball-iloat 41 floating on the molten wax switches olf the micro-switch 45 which thereupon switches off the heater 18.

The molten wax in the supply tube 23 and porous bushes 214 is caused by capillary action to deposit an oily film of molten wax on the surface of the porous bushes 24 whereby yarn passing over the porous bushes 24 becomes impregnated with the molten wax and is effectively lubricated.

The molten wax in the supply tube 23 and the porous bushes 24 is maintained at the required temperature and fluidity by the electric tape heater 46 located in the molten wax.

The level of the molten wax in the reservoir 20 and in the supply tube 23 and porous bushes 24 is controlled by the ball-float 41 through the operation of the microswitch 45.

Should the level of the molten wax fall below the predetermined level the ball-oat 41 moving downwards operates the micro-switch 45 and the electnic heater 18 is switched on to melt more of the solid wax in the melting chamber 13 until the molten Wax again reaches the prescribed level when the ball-iloat 41 rising switches ol the micro-switch 45 and the electric heater 18 is switched off.

The time delay switch 50 is controlled by the ballfloat 41 so that it only operates -if the electric heater 18 melting the wax in the melting chamber 13 has not restored the level of the molten wax in a predetermined time, eg., six minutes, thus ensuring that the

heaters

18 and 46 will not operate and, therefore possibly overheat, if there is no supply of molten wax in the reservoir 20. In the event of there not being a supply of solid wax in the melting chamber 13, the micro-switch stays on and the

heaters

18 and 46 remain in operation for the specied six minutes when the time-switch `t) operates and switches off the heater 18, at the same time the red signal lamp 51 is illuminated whereby to indicate to the operator that the supply of solid Wax in the melting chamber 13 is exhausted. When the operator has replenished the supply of solid wax he presses the re-set button 52 whereupon the electric heater 18 is again switched on and melting of the wax is resumed until, when the required level is reached and the ball-float 41 again operates the microswitch 45 to switch off the heater 18.

The level of the molten wax cannot rise above the predetermined level under normal conditions as the heat is cut-olf as soon as the ball-float 41 rises to the predetermined height and operates the micro-switch 45.

In the event of the thermostat 48 failing to function for any unforseen reason then the over-riding thermostat 53 operates to switch the plant ofr" completely and illuminates the red signal lamp 51 to indicate to the operator what has transpired.

` The junctions of the supply tube 23 and the porous bushes 24 are completely sealed whereby ingress of dust to the interior is prevented and also the escape of odours is prevented or minimised.

By the use of molten wax as a lubricant the amount of wax applied to the yarn is the same irrespective of time, whereas when a solid wax disc is employed as a lubricating means the solid wax disc varies as the mass decreases.

Generally, the harder the wax the better the lubricating properties but the more diflcult it is to apply in solid form.

With the present invention any Wax may be used irrespective of its hardness as the heating means effectively reduces it to the required state of fluidity for application to the yarn.

Referring to the schematic diagram shown in FIG. 7, the parts referred to in the foregoing description are indicated by the same reference characters.

The live and neutral wires are indicated respectively by the references L and N. 501 indicates the clock motor, 502. a clock fuse, 503 clock contacts, 504 a timer contact, 505 a relay and '506, 507 and 508 relay contacts. The circuit is earthed to the casing 10.

In the moditication of the invention illustrated in FIG. 8 of the drawings, the same principle of capillary action operates as has been previously described. In this simplified construction 61 indicates a trough containing a supply of paraffin wax indicated at P W., and 62 indicates a cylindrical porous iron bush with 30% to 40% voids. The bush 62 is suspended in a metal strap 63 secu-red to the underside of the cover `64- by means of screws 65 and nuts 66, and projects through a `slot y67, in the cover 64, the bush 62 fitting closely against the edges of the slot 67. 68 indicates a heating element of the tape type, i.e., a woven glass libre tape embodying resistance wires. The heating tape 68 is threaded through the porous bush 62 and dips into the wax in the trough 61 and is connected to a source of supply of electric current.

The current being switched on the heat from the tape 68 melts the wax in the trough 61 and by capillary action the tape y68 acts as a wick to feed molten wax into the interior of the porous bush `62 which is itself heated by 6 the tape 68 and by capillary action the molten wax penetrates the porous iron bush 62 to form a lm of molten wax on the exterior surface of the porous bush 62. Yarn indicated at Y being traversed over the oily su-rface of the porous bush 62 absorbs molten wax and is eliciently lubricated.

An advantage of this method is the quicker starting from cold since only the porous bush 62 needs to be heated and there is no necessity to wait for the bulk reserve of wax in the trough 61 to melt.

A further advantage is that the wax used may be chosen for its cheapness or lubricating power and need not be adulterated Kto soften it, or emulsiied as in conventional processing.

The cover 64 is a close lit on the trough 61 and the projecting portion of the porous bush 62 is a close tit in the slot y67 of the cover 64, the slot 67 also being closed at opposite ends by the wall of the bush 62.

The length of the porous` bush 62 is such as to completely lill the slot 67 in the cover 64. In this way ingress of dust to the interior of the trough is prevented and also the escape of odours from the trough 61 is prevented or minimised.

The trough 61 and porous bush 62 may be of any convenient length as required.

We claim:

1. Apparatus for applying a liquid lubricant medium to textile yarn or thread fed onto a yarn winding machine comprising an insulated casing, a melting chamber l0- cated inside said casing to receive a supply of hard Wax, an electrical heating element located below the melting chamber, and connected t0 a source of supply of electric current, a reservoir below the melting chamber to receive molten wax flowing from the melting chamber, a sieve interposed between said melting chamber and said reservoir; an outlet from said reservoir, la supply tube coupled to said outlet and extending along the whole length of one side of the winding machine to receive a supply of molten wax, a multiplicity of porous bushes intercalated in the connection to said tube at spaced intervals, there being a porous bush for each spindle of the winding machine; au electrical heating element connected to a source of supply of electric current, and extending through the tube and porous bushes from end to end and being immersed in the molten wax owing through the tube and porous bushes.

2. Apparatus for applying a liquid lubricant medium to textile yarns and threads as claimed in claim 1, further including a thermostat intercalated in the electric circuit of the heating tape, the bulb of the thermostat being located in the molten wax supply tube adjacent to the casing, whereby to control the temperature of the molten wax in the supply tube and porous bushes and maintain it at a predetermined level.

`3. Apparatus for applying liquid lubricant to textile yarns or threads as claimed in claim 1, in which the pcrous bushes are of porous iron with 30% to 40% voids, the pores being free enough to lift the molten wax so that it penetrates the porous material to Iform a hlm of molten wax on the exterior surface of the porous bush.

4. Apparatus for applying a liquid lubricant to textile yarns and threads as claimed in claim 2, further including a ball-iloat adapted to lioat on the molten wax in the reservoir and in association with a micro-switch in the electric circuit of the heating element of the melting chamber, whereby when the level of molten wax goes down the ball-float switches the micro-switch on thus causing the heating element of the melting chamber to melt more wax and so raise the level of the molten Wax, the micro-switch then `switching olf the said heating element.

5. Apparatus for applying a liquid lubricant medium to textile yarns and threads as claimed in claim 4, further including a time delay switch, a signal lamp adapted to show a red light and va re-set button in the circuit of the heating element of the melting chamber, characterised in that if there is no wax in the melting chamber, the aforesaid micro-switch remains on and when it has been on for a predetermined time the time delay switch illuminates the red signal lamp so giving visual warning that the melting chamber is empty and at the same time switches off the heating element of the melting chamber, whereupon the operator rst rells the melting chamber with solid wax and presses the re-set button to switch on the said heating element to resume heating of the wax.

6. Apparatus for applying liquid lubricant medium to textile yarns or threads as claimed in claim 4, having a ball-float in the reservoir of the casing and in operative association with la micro-switch in the electric circuit of the heating element of the melting chamber, characterised in that the level of the molten wax cannot rise above its predetermined level under normal conditions as the heat is cut off as soon as the ball-lloat rises to a predetermined height when the carrier arm of the ball-float operates the micro-switch to cut-out the heating element.

7. Apparatus for applying liquid lubricant to textile yarns or threads as claimed in claim 5, having a time delay switch in the electric circuit of the heating element in the melting chamber and in operative association with a ball-float, characterised in that the time delay switch is set in operation by the ball-oat and only operates if the heating element of the melting chamber melting the solid wax has not restored the level of the molten wax in a predetermined time, viz. six minutes, thereby ensuring that the heating elements will not continue to operate and possibly overheat if there is no supply of molten wax in the reservoir.

8. Apparatus for applying a liquid lubricant medium to textile yarns and threads as claimed in claim 5, further including an over-riding thermostat located in the molten wax reservoir, associated with a red signal lamp; the purpose of the over-riding thermostat being that in the event of the heat control thermostat failing to operate from any cause the over-riding thermostat switches the plant oft" completely and illuminates the red signal lamp.

9. Apparatus for applying a liquid lubricant medium to textile yarns or threads as claimed in claim 8, further including a signal lamp in the electric circuit of the heating element, means for switching on said heating apparatus simultaneously with a signal adapted to show an `amber light to indicate that the plant is alive.

10. Apparatus for applying lubricant medium to textile yarn or thread fed onto a yarn winding machine comprising a metal tube the surface of which has a large number of capillary pores, -a substantial portion of the body of said tube being porous, means for melting a solid lubricant, a connection `from said means to said tube for feeding molten lubricant to the interior of said tube to till the same, the pores of said tube being such size that the lubricant passes through the wall of said tube by capillary action forming a film of molten lubricant for application to the said textile by contact thereof with said surface.

11. Apparatus for applying a liquid lubricating medium to textile yarn or thread as claimed in claim 10, characterized in means whereby the lubricating medium is first heated to reduce it to desired fluidity, means is provided for maintaining said lubricating medium at a desired constant temperature to maintain iluidity; means is provided for maintaining said lubricating medium at a predetermined supply level whereby each yarn or thread from a multiplicity of spindles receives a uniform coating of lubricant irrespective of room temperature; and means whereby visual warning is given when the supply of liquid lubricant falls below the predetermined level.

12. Apparatus as claimed in claim 10, further characterized by means for heating the lubricant medium in the tube.

`13. Apparatus as claimed in claim 12, further characterized in that the means ytor heating the lubricant medium in the tube comprises an electric heating tape.

14. Apparatus as claimed in claim 13, further characterized in that the electric heating tape is submerged in the lubricant medium with the tube.

15. Apparatus as claimed in claim 13, further characterized in that the electric heating tape is arranged t0 act as a Wick to carry the lubricant medium into and onto the interior face of the tube.

16. Apparatus as claimed in claim 14, further characterized by having means for pre-heating the lubricant medium and applying it to the interior of the tube.

17. Apparatus for applying lubricant medium to textile yarn or thread fed onto a yarn winding machine cornprising a metal tube, the surface of which has a large number of capillary pores, a substantial portion of said body being porous, a trough containing a supply of wax, said tube fixed in said trough and projecting above the sides thereof to provide a surface over which the yarn traverses, an electric heating element embodying resistance wire connected to a source of supply of electric current for melting said wax, said heating element dipping into said wax in said trough and being threaded through said tube, the pores of said tube being of `such size that the wax passes through the wall of said tube by capillary action forming a lm of molten wax for application t0 said textile by contact thereof with said surface, whereby the heating element melts the wax in said trough when the current is switched on and the molten wax penetrates by capillary action said tube to lform a film of molten wax on the exterior surface thereof.

References Cited in the le of this patent UNITED STATES PATENTS 1,457,217 Dostal May 29, 1923 1,769,250 Arvidson .Tuly 1, 1930 2,325,129 Hardy July 27, 1943 2,333,543 Martin Nov. 2, 1943 2,470,093 Crowder May 17, 1949 2,539,953 Hoifecker Jan. 30, 1951 2,623,496 Lowell Dec. 30, 1952 2,908,246 Alexander et al Oct. 13, 1959 FOREIGN PATENTS 175,322 Switzerland May 1, 1935