US2900783A

US2900783A - Yarn crimping apparatus

Info

Publication number: US2900783A
Application number: US543361A
Authority: US
Inventors: Ralph H Carter; Chadwick B Kingsbury; Douglas J Lamb
Original assignee: North American Rayon Corp
Current assignee: North American Rayon Corp
Priority date: 1955-10-28
Filing date: 1955-10-28
Publication date: 1959-08-25
Anticipated expiration: 1976-08-25

Description

Aug. 25, 1959 Filed Oct. 28, 1955 R. H. CARTER ET AL 2,900,783

YARN CRIMPING APPARATUS e Shets-Sheet 1 F I 6. I.

w IN VEN'fgRS RALPH l-LOARTER GHADWIOK a. muesaumr DOUGLAS a. LAMB 2%,; ATTORNEY g- 1959 R. H. CARTER ET AL 2,900,783

YARN CRIMPING APPARATUS Filed Oct, 28, 1955 6 Sheets-Sheet 2 l N s l' I I1 w Q Q w S RALPH l'l. CARTER CHADWICK B.KING$BURY DOUGLAS J. LAMB I m 94 J 7 25; ATTORNEY Aug. 25, 1959 R. H. CARTER ET AL YARN CRIMPING APPARATUS Filed Oct. 28, 1955 FIG. 2.

1 CHADWICK B. DOUGLAS llllll- ALPH H.

INVENTLJRS CARTER KINGSBURY J. LAMB MTTORNEY Aug. 25, 1959 R. H. CARTER ET AL 2,900,783

YARN CRIMPING APPARATUS Filed Oct. 28, 1955 6 SheetsSheet 4 INVENTORS 22 RALPH H. CARTER @HADWICK B. KINGSBURY DOUGLAS J. LAMB Aug. 25, 1959 R. H. CARTER ET AL 2,900,783

YARN CRIMPING APPARATUS Filed Oct. 28, 1955 6 Sheets-Sheet 5 L 'IIIII'IIIIIII. A

TTORNEY 1959 R. H. CARTER .ET AL 2,900,783

YARN CRIMPING APPARATUS Filed Oct. 28, 1955 6 Sheets-Sheet 6 7.; Y ze FIG.9.

-||||1![ I M llllllIlllig 6.5 5/

i JJ .77 3

IN VENTORS RALPH H. CARTER OHADWIGK B. KINGSBURY DOUGLAS J. LAMB 7 j ATTORNEY United States Patent C YARN CRllVIPlN G APPARATUS Ralph H. Carter, Johnson City, and Chadwick B. Kingsbury and Douglas J. Lamb, Elizabethton, Tenn., assignors to North American Rayon Corporation, New York, N.Y., a corporation of Delaware Application October 28, 1955, Serial No. 543,361

Claims. (Cl. 57-34) This invention relates to an apparatus and method for crimping nylon and similar thermoplastic synthetic yarns.

An object of this invention is to provide an improved apparatus for crimping nylon and similar thermoplastic yarns uniformly and with high efficiency with comparatively little operator attention.

Another object of this invention is to provide an improved apparatus for crimping nylon and similar thermo plastic yarns in a continuous process.

Still another object of this invention is to provide an improved crimping apparatus in which the parts are readily assessible for cleaning and for threading up the apparatus.

Another object of this invention is to provide an improved crimping apparatus in which yarn containing false twist is uniformly heated by convection while passing through a heated tube to produce uniformly crimped yarn.

Still another object of this invention is to provide an improved crimping apparatus having a plurality of tubes for simultaneously uniformly heating several strands of running yarn by convection, said tubes extending through a chamber through which hot oil or other heating medium is circulated to produce said uniform heating.

Another object of this invention is to provide an improved crimping apparatus having a plurality of tube heating chambers which are so arranged that the mean temperature of all of the tubes through which the yarn being crimped isrunning, it substantially the same.

Still another object of this invention is to provide an improved continuous crimping apparatus in which the running thread is maintained under substantially constant tension by means of a compensating tension arrangement in which variations in yarn tensions vary the setting of the tension device so as to correct at once any tension variations.

Another object of this invention is to provide an improved crimping apparatus having a tension device, a yarn heating tube and a false twist spindle in which contact of the running yarn with surfaces of the apparatus between the tension device and the yarn coupling block of the false twist spindle is kept at a minimum in order to produce uniformly crimped yarn.

Still another object of this invention is to provide an improved continuous process for crimping nylon or other thermoplastic synthetic yarn in which the yarn is plasticized by heating While it is under substantially uniform tension and is uniformly twisted by a false twist spindle, all of these steps in the crimping process being performed on the yarn while it is extended in a substantially straight line so as to produce yarn that is substantially uniformly crimped.

Another object of this invention is to provide an improved continuous process for crimping nylon or other thermoplastic yarn by softening the yarn and immediately thereafter twisting it, at the same time keeping it out of contact with surfaces of'the apparatus .in the ice heating zone so that the false twist can run back uniformly on the yarn through the entire heating zone.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specifications and claims.

In common types of crimping apparatus, the yarn in its travel through the apparatus contacts various thread guides, heating shoes, and other devices which deflect the path of yarn travel and introduce non-uniformity in the crimp in the yarn before it has had an opportunity to set. It has been found that twist uniformity is disturbed whenever the path of yarn travel is deflected by contact with a thread guide, a heating shoe or the like and it has also been found that yarn is not heated and softened uniformly by contact with a heating shoe. The apparatus of the present invention was constructed to produce uniform twist. In this apparatus the yarn travels in free straight line flight through the heating zone where it is uniformly heated by convection and not by direct contact with hot surfaces of the apparatus.

Furthermore, in accordance with this invention the thermoplastic yarn to be crimped is heated while it is under substantially uniform tension and at the same time it is uniformly twisted by a false twist spindle. The heat softens the yarn and permits the twist to set so that a crimp remains after the yarn passes through the false twist spindle. The yarn is thereafter wound on a suitable take-up device.

The substantially uniform yarn tension is obtained by the use of a compensating tension arrangement in which variations in the tension of the running yarn vary the setting of the tension device so that the yarn tension variations are at once corrected. Special precaution is taken to see that the twist imparted to the yarn is uniform between the aforesaid tension device and the false twist spindle. During this travel contact of the yarn with surfaces of the apparatus is kept at a minimum and further precaution is taken to prevent introduction of non-uniform twist into the yarn. This comprises the use of an improved type of spindle.

Additional features of this invention reside in the novel construction and assembly of the thread heating tubes whereby uniform heating of a plurality of yarn strands is obtained simultaneously. This uniform heating is accomplished by circulating oil or other heating fluid through heating chambers which surround each group of heating tubes through which the yarn strands pass. A section of the machine consists of a plurality of elongated vertically positioned heating tubes passing through a heating chamber through which oil or other heating medium is circulated and a false twist spindle is positioned externally of each heating tube so that their axes coincide. This arrangement makes it possible for the yarn to be crimped to be drawn from. the tension device in a straight line through the heating tube without contacting the tube wall or any other machine surface until it reaches the yarn coupling block of the false twist spindle. Furthermore, the twist inserted by the spindle runs back uniformly on the thread to the tension device since there is little if any contact between the yarn and the heating tube. The temperature of the air in the heating tube is such that the yarn is plasticized sufiiciently bottom section of the first heating chamber of the machine. From the first heating chamber the heating fluid passes to the bottom section of the second chamber of the machine and from there to the third heating chamber, etc. After leaving the bottom section of the last heating chamber of the machine, the heating fluid is caused to return through the top sections of the chambers in a similar manner, passing from the last chamber of the machine back to the first heating chamber. It will be readily seen that if the heating fluid enters the machine at, for example, 450 F. and leaves it at 430 F., the average temperature of each heating chamber will be 440 F. As a result the air temperature within each heating tube of the machine will be the same.

Other and further features of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims and drawing in which briefly;

Fig. 1 is a view in side elevation of the upper portion of one section of a machine of this invention;

Fig. la is a view in side elevation of the lower por tion of a machine section such as is shown in Fig. 1;

Fig. 2 is a vertical sectional view taken on line 22 of Figs. 1 and la;

Fig. 3 is a fragmentary side view, partially in section, of a heating chamber employed on a section of this machine;

Fig. 4 is a vertical view of the heating chamber taken 011 line 44 of Fig. 3;

Fig. 5 is an enlarged fragmentary sectional view of a yarn heating tube;

Fig. 6 is a sectional view taken on line 66 of Fig. 5;

Fig. 7 is a schematic view showing the arrangement for the circulating of heating fluid through a plurality of heating chambers;

Fig. 8 is an elevational view of a false twist spindle;

Fig. 9 is a vertical sectional view taken on line 99 of Fig. 8;

Fig. 10 is a plan view of the false twist spindle shown in Fig. 8; and

Fig. 11 is an enlarged fragmentary perspective view showing the passage of the yarn through the false twist spindle.

Referring to the drawings in detail, the same reference numerals are employed in each of the views for corresponding parts. There is shown in the several views of the drawing one six place section of the crimping apparatus. A section may consist of fewer or more than six yarn crimping places and several sections may be placed end to end and back to back to constitute a machine.

Each of the sections consists of a frame 10 in the lower part of which supply board 11 is mounted as shown in Figs. 1, la and 2. A plurality of pirns or other yarn supply packages 12 are suitably positioned on the supply board 11. Yarn collecting guides 13, secured to structural member 14 of frame 10, are positioned directly above the yarn supply packages 12.

Structural member 14 also supports compensating tension devices 15 of the type disclosed in US. Patent No. 2,554,493. The yarn passes through the thread guide 16 and then it passes between the discs 15a and 15b of the tension device 15. A thread guide 18 is provided at the end of a tension sensing and regulating arm 17 of the tension device 15 and the yarn engages this latter guide as it leaves the tension device. The arm 17 controls the spacing of the discs 15m and 15b so that when an increase in yarn tension lifts arm 17 the discs 15a and 15b are moved apart to reduce the yarn tension.

A decrease in yarn tension allows arm 17 to drop and- A heating chamber assembly 20 is supportedby horizontal threaded

rods

21 and 22 which are rigidly secured to the chamber and to longitudinal structural members 23 and 24, which, in turn are secured to frame 10.

Lock nuts

25 and 26 secure chamber 20 adjustably to members 23 and 24 so that the chamber may be shifted laterally on the frame members 23 and 24.

Heating chamber assembly 20 consists of a plurality of spaced elongated cylindrical yarn heating tube assemblies 27 extending through the chamber assembly as shown in Figs. 3 and 4. The yarn heating tube assemblies 27 such as shown in Fig. 5, pass through a heating chamber 28, which is divided by a horizontal baflle 29 into upper section 30 and lower section 31.

A suitable heating fluid is circulated through the upper and

lower sections

30 and 31 of heating chamber 28. Fig. 7, schematically shows the circulation of the heating fiuid through a plurality of heating chambers such as shown in Figs. 3 and 4. The lower section 31 of each heating chamber 28 has a heating fluid inlet 49 at one end of the chamber and an outlet 50 at the opposite end. The upper section 30 of each heating chamber 28 has a similar but oppositely disposed fluid inlet 51 and fluid outlet 52. The outlet of the lower section of a chamber is connected to the inlet of the lower section of an adjacent chamber so that there is series flow of heating fluid through the bottom sections of all the heating chambers and the heating fluid is then circulated through the top sections of the same chambers so that there is series counter-flow through the upper sections of the same chambers as shown by the arrows in Fig. 7. Heating fluid at constant temperature is supplied to the system by any suitable conventional apparatus. It will be seen that the heating fluid entering the lower section of the first heating chamber of a machine is at a maximum temperature and that there is a certain temperature drop as it passes through the lower section of each chamber. There is also a similar temperature drop as the heating fluid returns through the upper sections of the same heating chambers. Due to the fact that the flow of heating fluid through the upper sections is counter to flow through the lower sections, the average temperature of each chamber is the same and consequently the air temperature is the same in each yarn heating tube of the machine. That is, the average temperature of the heating chambers is the average of the temperatures of heating fluid at the inlet and at the outlet of the circulating system. In order to hold to a minimum the temperature drop of the heating fluid during its passage through the heating chambers 28, each chamber 28 is enclosed by a jacket 32 and suitable insulating material 31a is provided between the heating chambers and their respective jackets.

As shown in Fig. 5, each heating tube assembly 27 consists of a cylindrical tube 53 having upper and lower thread guide eyelets 54 and 55 respectively, upper and lower eyelet retainer discs 56 and 57, upper and lower funnel-shaped thread-up wire guide members 58 and 59 and upper and lower retainer rings 60 and 61. The funnel-snaped members 58 and 59, the thread guide eyelets 54 and 55, and eyelet retainer discs 56 and 57 are held in place against

shoulders

62 and 63 by retainer rings 60 and 61. The heating tube assemblies 27 are secured in a fluid tight manner to the upper and lower surfaces of heating chamber 28 where the tubes pass therethrough.

A spindle drive belt 33 is driven by pulley $4 and guided along the machine by idlers 35 which are attached to longitudinal member 36 of frame 10 as shown in Figs. 1 and 2.

A false twist spindle assembly 37 is positioned coaxially above each yarn heating tube 27 as is also shown in Figs. 1 and 2. The false twist assembly per se is the subject of co-pending application Serial No. 543,362, filed concurrently herewith, now US. Patent No. 2,813,393. The spindle assembly is shown in detail in Figs. 8, 9, l0 and 11 and each such spindle assembly 37 is supported by swing arm 38, which is pivotally attached to longitudinal member 39 of frame by a pivot 40, in such a manner that the rotating member of the spindle assembly False twist spindle assembly 37 consists of a rotatable twist tube 64 having an axial bore 65. A yarn guide bushing 66 is secured in the lower end of this bore and a yarn coupling block 67 is secured to the upper end of twist tube 64 by means of coupling block retainer 68.

Yarn coupling block 67 is provided with a vertical bore 69 co-axial with bore 65 of twist tube 64, and a pair of

horizontal bores

70 and 71 disposed on either side of and adjacent to axial bore 69 as shown in Fig. 11. The yarn coupling block is preferably an insert so that it can be made of materials such as stainless steel, a ceramic, or the like, which have suitable wear resisting and frictional properties. Each end of axial hole 69 and each end of

lateral holes

70 and 71 are chamfered to prevent chafing of the rlmning thread. Yarn coupling block 67 is secured in retainer 68 by press fit or by set screws, pins, or the like, and retainer 68 is secured in a similar manner to the top portion of the twist tube 64.

Yarn coupling block retainer 68 is an inverted cup-like member having an axially located thread guide opening 72 in upper portion 73 of the retainer and oppositely disposed side ports 74 and75 to provide access to the yarn coupling block when threading up. Shoulders 76 in the upper portion of retainer 68 bear against the upper end of the coupling block and hold it in position against the top of the twist tube.

Twist tube 64 is rotatably supported in the member 81 by upper ball bearing 77 and lower ball bearing 78. An annular rubber boot 79 having a U-shaped crosssection is disposed about the outer race of upper ball hearing 77 and a similar annular rubber boot 80 also of U-shaped cross-section is disposed about the race of lower ball bearing 78. These rubber boots absorb vibrations produced in the spindle.

The housing 81 has a seat 82 to receive the upper ball bearing 77 and rubber boot 79 assembly that is held in place by snap ring. 83. A cylindrical bore 84 in housing 81 receives the lower ball bearing 78 and rubber boot 80 assembly. Washer 85, secured to twist tube 64 immediately above lower ball bearing 78 acts as a slinger to protect the lower ball bearing from the accumulation of foreign material resulting chiefly from wear on the belt 33. Housing 81 is provided with a cut-out portion 86 so that the drive belt 33 can contact twister tube 64 and cause it to rotate.

A yarn collecting guide 41, supported by longitudinal member 42 of frame 10, is positioned above each false twist spindle assembly 37. A conventional traverse guide 43 is positioned above each yarn collecting guide 41. Traverse guides 43 are secured to a longitudinal traverse bar 44, which is movably supported by a roller 45 attached to longitudinal structural member 46 of frame 10. A conventional yarn take-up spool 47, supported on and frictionally driven by take-up roll 48, is also provided for each position of the machine. Take-up roll 48 is supported and driven in a conventional manner.

In the operation of this machine nylon or other thermoplastic yarn 87 is drawn from supply package 12, through collecting eye 13 and compensating tension device 15. From the thread guide 18, at the end of tension sensing and regulating arm 17 of tension device the yarn passes vertically in a straight line through eyelet guides 55 and 54 and the bore of heating tube assembly 27 with very little if any contact between the yarn and the heated inner surface of the tube. The yarn is therefore heated uniformly throughout by convection and radiation. The yarn enters yarn guide bushing 66 of twist tube 64 and continues in a straight line through bore 65 of the twist tube and axial hole 69 of thread coupling up wires, hooks, etc. Due to the simple construction of block 67, thence across the top of the coupling block, down its side and through either

horizontal hole

70 or 71, thence up the opposite side of the coupling block and out through axial thread guide opening 72 of retainer 68.

The yarn'is so coupled to the spindle by its tortuous passage through the axial and horizontal holes of the coupling block that one turn of false twist is always inserted in the yarn below the coupling block for each revolution of the spindle. This false twist extends back to a point of radial contact at the guide 18 of the compensating tension device. Because the twist runs back uniformly through the heating zone where the yarn is plasticized and because the twist is undisturbed by physical contact with the machine in this zone, a very uniform crimp is produced. It is, of course, important that the axis of the tube 64 of the twister be aligned with the axis or center of the heating tube 27 in order to prevent contact between the yarn and these tubes.

The yarn may be threaded through the heating tube and the false twist spindle by means of well-known threadthe spindle it is practically impossible to thread it up in correctly. It will be understood that the yarn may be passed through either horizontal hole 78 or horizontal hole 71 of the coupling block.

The yarn leaving the false twist spindle is drawn through collecting guide 41 and is guided on the take-up package by the traverse guide 43.

A uniform and pronounced crimp is produced in a continuous manner in this apparatus. The false twist produced by the spindle runs back uniformly to the tension device because the yarn contacts no part of the machine between the spindle and the tension device. While the yarn containing this false twist is passing through the heating tube it is sufliciently heated by convection and radiation to uniformly soften the yarn and so set the twist. The twist being set, crimp remains when the yarn unt-wists as it leaves the false twist spindle. The amount of crimp produced will, of course, depend to a large degree upon the amount of false twist inserted in the yarn. The maximum amount of twist which can be inserted in yarn will vary with the denier, number of filaments, etc.

The amount of crimp produced depends also on the efiiciency of the twist setting obtained in the heating tube. To secure the maximum crimp it is necessary to heat the yarn to such a temperature that the twist is set completely. However, the yarn should not be heated to such extent that resulting filament adhesion is not removed by passage of the yarn through the yarn coupling member 67. Lower temperatures give increasingly inferior crimp. If filament adhesion persists in the finished yarn the product will be inferior because the filaments are not open and free to contract. An inferior crimp will be obtained if the yarn touches the inner surface of the heating tube because this heats and softens the yarn non-uniformly. It has been found that the optimum air temperature within the heating tube is 440 F. for nylon 6, 6 and 375 F. for nylon 6 at the tube length of 12 inches and a take-up speed of 12 yards per minute in the range of 30 to denier.

The uniform tension in the yarn heating and softening zone which results from the use of the compensating tension arrangement to control the input tension and from the use of a false twist spindle having a-non-rotatable coupling member which gives a uniform added tension contribute to the production of a uniformly crimped yarn of uniform denier.

It has been found that the crimp is not at all adversely affected by winding the yarn onto the take-up package nylon monofil and the multi-filament nylons now on the market, i.e. from 15 denier to 840 denier.

To crimp 7O denier multi-filarnent nylon 6, 6 by this process and apparatus the air temperature in a 12 inch long heating tube may be 440 F., the yarn travel 353 inches per minute and the false twist spindle rotating at 30,000 r.p. a. to give 85 turns of false twist per inch. (Tests have shown that this calculated false twist is actually produced.) The yarn tension in the heating tube should be 10 grams and the yarn tension above the spindic should be 12-18 grams. The yarn has a pronounced and permanent crimp.

While we have described this invention in detail with respect to certain preferred embodiments thereof, it is, of cour c, not desired to limit the invention to the exact details described and illustrated except in so far as those details are defined by the claims.

What we claim is as follows:

1. An apparatus for substantially uniformly crimping thermoplastic yarns comprising the combination of means for heating and softening a plurality of strands of thermoplastic yarn, said means comprising a plurality of tubular members through which said yarn strands are adapted to pass, said tubular members being arranged in groups, a plurality of fluid conducting heating chambers positioned around upper mid lower portions of said tubular mem bers respectively, one of said chambers being positioned around each of said groups, each of said chambers being partitioned into an upper section and a lower section, means for connecting said lower sections in series, means for connecting said upper sections in series, means for conncs'ng the end of the upper section to the end of the lower section in the end chamber of the series, means for feeding heating fluid first through the lower sections of said series of chambers and returning said heating fluid through the upper sections of said series of chambers to provide substantially uniform heating of all of said tubular members, means for passing individual yarn strands to be softened through said tubular members, and means for uniformly crimping all of said yarn strands.

2. An apparatus for substantially uniformly crimping thermoplastic yarns comprising the combination of means for heating and softening a plurality of strands of thermoplastic yarn, said means comprising a plurality of tubular members through which said yarn strands are adapted to pass, said tubular members being arranged in groups, a plurality of fluid conducting heating chambers positioned around said tubular members, one of said chambers being positioned around each of said groups, each of said chambers being partitioned into an upper and a lower section, means for connecting the upper sections in series, means for connecting the lower sections in series, means for connecting the end of the upper section to the end of the lower section in the end chamber of the series, means for feeding heating fluid through the one of said sections of the series of chambers and returning said heating fluid through the other of said sections of the series of chambers to provide substantially uniform heating of all of said tubular members, means for passing individual yarn strands to be softened through said tubular members, and means for uniformly crimping all of said yarn strands.

3. An apparatus for substantially uniformly crimping thermoplastic yarns, comprising a plurality of tubular members through which yarn is adapted to pass, a heating chamber havin" an upper section positioned about the upper portions of said tubular members and a lower section positioned about the lower portions of said tubular members, means for feeding heating fluid through one of said sections and about said tubular members, means for returning the heating fluid through the other of said sections and about said tubular members to provide substantially uniform heating of all of said tubular members, means for passing individual strands of yarn through said tubular members, and means for uniformly crimping said strands of yarn.

4. An apparatus according to claim 3 wherein the ends of said tubular members are provided with restricting means whereby air currents within said tubular members are minimized, said restricting means having a relatively small opening located axially of said tubular member whereby a strand of yarn may pass freely therethrough.

5. An apparatus according to claim 4 wherein said restricting means have a funnel shape facing the inside of said tubular member to facilitate the threading up of said tubular member.

6. Apparatus for heating and softening strands of thermoplastic yarn, comprising a plurality of tubular members through which yarn is adapted to pass, a heating chamber having an upper section positioned about the upper portions of said tubular members and a lower section positioned about the lower portions of said tubular members, means for feeding heating fluid through one of said sections and about said tubular members, and means for returning the heating fluid through the other of said sections and about said tubular members, whereby the heating of said tubular members is substantially uniform.

7. Apparatus according to claim 6 having means restricting the ends of said'tubular members whereby air currents within said tubular members are minimized, said restricting means having a relatively small opening located axially of said tubular member whereby a strand of yarn may pass freely .therethrough.

8. Apparatus according to claim 7 wherein said restricting means have a funnel shape facing the inside of said tubular member to facilitate the threading up of said tubular member.

9. Apparatus for heating and softening strands of thermoplastic yarn, comprising a plurality of tubular members through which yarn is adapted to pass, said tubular members being arranged in groups, a heating chamber positioned about each of said groups of tubular members, each of said heating chambers having an upper section positioned about the upper portions of said tubular members and a lower section positioned about the lower portions of said tubular members, means for feeding heating fluid in series flow through one of said sections of said heating chambers, and means for returning the heating fluid in series flow through the other of said sections of said heating chambers, whereby the heating of said tubular members is substantially uniform.

10. Apparatus for heating and softening strands of thermoplastic yarn, comprising a plurality of tubular members through which yarn is adapted to pass, said tubular members being arranged in groups, a heating chamber positioned about each of said groups of tubular members, each of said heating chambers having an upper ection and a lower section, means for connecting said lower sections in series, means for connecting said upper sections in series, means for connecting the upper and the lower sections of the end chamber of the series, and means for feeding heating fluid through the lower sections of said series of chambers and returning the heating fluid through the upper sections of said series of chambers, whereby the heating of said tubular members is substantially uniform.

References Cited in the file of this patent UNITED STATES PATENTS 2,089,229 Taylor Aug. 10, 1937 2,089,239 Whitehead Aug. 10, 1937 2,089,240 Whitehead Aug. 10, 1937 2,090,352 Herrmann Aug. 17, 1937 2,111,209 Dreyfus Mar. 15, 1938 2,111,211 Finlayson et al Mar. 15, 1938 2,199,411 Lewis May 7, 1940 2,477,909 Stockly Aug. 2, 1949 2,790,298 Kunzle Apr. 30, 1957 2,803,109 Stoddard et a1 Aug. 20, 1957