US2315763A

US2315763A - Lug strap

Info

Publication number: US2315763A
Application number: US363121A
Authority: US
Inventors: Henry M Bacon
Original assignee: Dayton Rubber Manufacturing Co
Current assignee: Dayton Rubber Manufacturing Co
Priority date: 1940-10-28
Filing date: 1940-10-28
Publication date: 1943-04-06
Anticipated expiration: 1960-04-06

Description

April 6, 1943.

H. M. BACON LUG STRAP 2 Sheets-Sheet 2 Filed Oct, 28, 1940 .lEr.

INVE/{TOR v HENRY/7. BACON A TTOR/VE Y5 chinery.

Patented Apr. 6, 1943 LUG STRAP Henry M. Bacon, Dayton, Ohio, assignor The Dayton Rubber Manufacturing Company,

Dayton, Ohio, a'corporation of Ohio Application October 28, 1940, Serial No. 363,121

' Claims. "(01. 139-153) My invention relates to improvements in lug straps used in weaving looms or similar ma- One important object of this invention is to provide a lug strap which'is constru'cted'so as to possess improved strength and exhibit greater resistance to wear and failure by fatigue under the action of heat.

Another object is to devise an improved method of making a lug strap wherein the formation of wrinkles or folds in the laminations or layers forming the U-shaped strap is avoided during manufacture.

Another object is to provide an improved lug strap wherein the strength and cushion sections are located at the point where it is required to give the greatest resistance to wear or impact strain resulting from the picker stick action.

These and other objects and advantages will be apparent to those skilled in the art during the course of the following description.

In the drawings:

Figure 1 is a perspective view illustrating the method of fabricating my improved lug strap by winding the difi'erent layers forming the body of the strap on a surface of a drum preparatory to cutting the built-up sleeve body into a strap or plurality of straps of the desired width; I

Figure 2 is a fragmentary sectional view taken through the drum surface and laminated sleeve sary to increase the strength and quality ofloom, Lug.

accessories and especially the lug straps. straps of greater strength are required because the actual picking blow is far greater than heretofore due to the higher speed at which the looms are operated and the employing of heavier shut. tles. subsequent shortening of the rest periods, has required that the loom picker possess the property of substantially instantaneously or very rapidly recovering its resiliency and strength after each pick or blow. Further, due to the increased speed of operation, the snap or. harshness of the pick or blow has been magnified. resultingin bringing about a greater strain on the picker sticks, which, in turn, has placed an added importance on the cushion or resiliency .of the lug strap.

body forming the body of the'lug strap and taken I substantially along the line 22 of Figure 1;

Figure 3 is a vertical sectional view illustrating the use of an expansible core and means for expanding same for forming the laminated band comprising a double lug strap into the desired shape whereby the same can be vulcanized toa tough, durable strap, after which the double strap can be severed to form a pair of lug straps; Figure 4 is a sectional view taken through a mold showing the built-up sleeve forming the lug strap body mounted on an expanded core and arranged in a mold cavity for vulcanizing the sleeve into a finished double lug strap;

Figure 5 is a similar sectional view taken through a mold showing a modification wherein an air bag is used for applying pressure to the inner side of the double lug strap during molding and vulcanizing of the same;

Figures 6 to 11 are sectional views of a lug strap made according to this invention wherein different laminated constructions are used for forming the lug strap.

In general, the higher speeds and heavier loads of the modern weaving looms have made it neces- To produce a lug strap having greater strength and resistance to fatigue and failure under the temperature and operating conditions of loom machinery, I have found that it is necessary to 7 construct a lug strap wherein the strength sec- ,tion is localized at the point of the greatest strength need, which is adjacent the outside of the strap. All of the power deliveredto the strap is from the inside, and, consequently, any materials or fabrication placed on the outside of the strength section are of little value-for adding strength to the lug strap. Furthermore, by localizing the strength or tension layer to a very thin area, the compressive forces which set up strains adjacent the neutral strength axis are reduced to a minimum.

When the strength section of the lugstrap is localized in the outside layers of the lug strap the entire remaining body can be made to functionas a cushion or resilient portion. This is very important because the cushioning obtained by compression is much better than that by tension or extension. There is also an added advantage in that a very rapid recovery of the lug strap to its normal resilient form is obtained by constructing the lug strap to provide cushioning of the picker blow by compression.

In order to produce a lug strap having the improved strength and uniformly distributed resistance to working stress and proper resiliency, it is necessary to eliminate any'possibility of the formation of wrinkles, folds, buckles, or flow strains during the lamination and molding of the lug strap. To this end, each section or layer forming the lug strap must retain its relative spacing and tension in the finished strap as in the unfinished stages. This has been the prime The increased speed of operation, with the cause of failure when the conventionally made rubber lug straps were changed from a very hard to a softer composition. Wrinkled and buckled portions, always present in the conventional rub ber lug straps, readily open up with the use of softer compositions or materials in the making of the lug strap. It has also been found that all the plies of a very hard conventional lug strap work. as a unit because of the rigidity of the binder holding them together. With a softer binder, the buckled inner pliesplace an added strain on the outer plies which are already under stress producing an inferior lug strap.

My invention overcomes the defectsmentioned and provides a strong, durable lug strap and a convenient and comparatively inexpensive method for manufacturing lug straps in large quantities with the minimum possibility of producing straps which are not uniform. The invention also provides a lug strap of improved structure made of materials which render the strap freefrom attack by rodents .and wherein wrinkles, buckles, or folds in the laminated layers forming the lug strap, with their resultant detrimental effects, are entirely eliminated and a strap is produced wherein the stress is uniformly distributed throughout the body of the strap.

Inthemanufacture of lug straps embodying the improved construction, I have built up the lug strap in the form of a laminated sheet body on a drum or mandrel, such as shown at [5 in Figure 1. There is applied around the surface of the drum a layer of cushion stock, generally designated I6, of desired thickness. This cushioning body portion may be formed, of several layers of rubberized fabric such as illustrated in Figure 6. Over the resilient cushioning layer i5" is wound a-cord layer forming the strength section ll. The cord is wound on under proper tension so that each strand bears its full share of the load. If desired, the cord-may be wound on slightly spiral. Over the cord layer I1 is applied a rubberized fabric covering to protect the cords from exposure. Sufficient rubberized fabric is placed under and over the cord layer to prevent the cords from separating. Preferably, strong, tough cords which are resistant to disintegration and wear are used.

The thickness of the resilient layer It is such as to provide the proper cushioning of the pick or blow and may be formed of any wear resistant resilient material. Other materials than rubber,

' such as glue, synthetic resin, or the like can be used for bonding the layers into an integral body. Any suitable combination of strength material and binder having the required thermoiiowing 7 Figures 6, 8 and 10;

ure 3, and means is provided, such as the right and left movable screw head members 24 for expanding the core sections 25 to form the U- shaped double strap 22. When the core portions 25 have been expanded to a proper-amount the center member 21 is placed in position to maintain the core sections 25 in their expanded position, as illustrated in Figure 4. Other suitable means maybe provided for expanding and maintaining the core 2| in its outermost position. The outer surface portions of the core sections 25 comprise an arcuate con ave surface 29 so as to provide a rounded surfa e portion on the inner side of the bow or bend which is transverse tothe longitudinal axis of the lug strap.

After positioning the core on the inner side of the double lug strap 22, the core and lug strap are placed in a mold having suitable complementary dies 3| and 32 which are shaped to form the cavity 34 in which thelug strap and core are positioned for vulcanizing the strap to a hard, tough, resilient body. Suitable means, such as steam or hot water, is circulated through the passageways 35 in order to heat the mold sections 3| and 32 to the desired temperature for curing the lug strap body 22. The mold parts 3| and 32 are shaped in such a manner as to leave a space 31 along the outer surface portion of the bend or bow of the lug strap so that the inner walls of the mold adjacent the outer surface of the lug strap at the bend do not contact the lug strap permitting proper expansion of the material during molding to equalize the stresses in this area and. prevent the formation of wrinkles or buckles in the laminations.

In the modification shown in Figure 5, the metal expanding core is replaced by an air bag 39 which is expanded by fluid pressure during molding and .vulcanization of the double lug strap. Other suitable methods may be employed for applying pressure to the inside of the lug strap during molding and vulcanization.

The essential feature in the molding of the lug strap is to apply the same pressure to the inside of the strap as to the outside so asto forma lug strap free from internal stresses such as would result from the formation of wrinkles or buckles in the body portion of the strap during shaping and molding oi the strap. For con- .veniencega double strap is formed which, after shaping, is severed in the middle formlng'two separate U-shaped lug straps, as illustrated in The usual slots 40 are made in the legs of the strap before or after and setting properties may beemployed but 1 i prefer to use rubberized fabric for this purpose. In this construction, the lug strap comprises a laminated body formed of rubberized fabric built up to the desired thickness which ismolded and vulcanized to produce a U-shaped strap.

After a sleeve of sufficient width is built up on the drum o mandrel l5, one or more lug straps of the desired width are out therefrom by the application of a knife. or other suitable means' such as shown at 20 in Figure 2. The bands which are produced by cutting the sleeve circumferentially at spaced intervals form integral pairs of lug straps. or buckling of the body portion of the lug strap during subsequent forming and molding of the double straps, an expansible core member, generally designated 2!, is placed on the inner side of the double strap member 22. as shown in Fig- In order to eliminate wrinkling severance of the double lug strap as desired. There may also be applied a cap 42, preferably made of'rubber, over'the outside of the bend or bow surface portion of the lug strap, as illustrated in Figures 6, 8 and 10, so as to improve the appearance of the lug strap. This gum cap, however, may be eliminated if desired without interfering with the working properties of the lug strap.

In Figures 6, 8 and 10 modifications in the construction of lug straps according to my invention are illustrated wherein the cushioning inner surface body of the lug strap is formed of different types of materials, such as laminated rubber fabric, Stiflex, or fabric encased rubher. The particular material used for forming the cushioning inner body portion of the lug strap is notimportant so long as the material is non-flowing under the heat and humidity conditions to which the lug strap is subjected in service. When the lug strap is built up of thermoflow resistant material, such as fabrics and the like, this diillculty is not encountered. However, with the use of a predominance of thermoilowable material, such as heat flowable resin, rubber, and the like, it is necessary to reduce this flow to a minimum so as to localize it to small areas. This may be accomplished by semicuring or setting the filler to the rubber or resin,

or encasing the same in non-fiowable material such as a fabric Jacket, similarly as shown in Figure l0.- Another method is to, load the heat flowable material with fibers oruse Stiflex. Coarse woven fabrics may also be used to present undue flowing of the-soft materials forming the cushion part of the lug strap.

. In the preferred embodiment of the lug strapa U-shaped body comprising the lug strap.

wherein the lug strap is made up of rubberized fabric layers for forming 'the cushion and outer cord layer, there is produced a superior lug strap which is free from wrinkles and buckles in the layers and has an exceptionally long life. Com-t parative test results have shown that lug straps made according to my invention last many times longer than conventionally constructed straps.

It is to be understood that my invention is not limited to the exact details of construction and the method of shaping and molding the lug straps, since obvious modifications within the scope of this invention may be made by those skilled in the art.

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

2. As an article of manufacture, a lug strap according to claim 1 wherein the cushion layer comprises laminated rubberized fabric.

3. As an article of manufacture, a lug strap according to claim 1 wherein the cushion layer comprises Stiflex.

4. As an article of manufacture, a lug strap according to claim 1 wherein the cushion layer comprises rubber composition encased in fabric.

. substantially thicker than said cord layer, said cushion layer and strength layer forming, respectively, the inner and outer outline of a U- shaped body comprising the lug strap.

HENRY M. BACON.