End-dressings for tubular casings

Improved strands of sausage casings having their filling ends dressed have fewer failures as a result of loose tab-ends. Residual casing material remaining on the end of the casing from severing from other casing material is made to cling to the terminal end by the application of compressive force and heat in a sufficient amount to avoid fusion of the casing material.

BACKGROUND OF THE INVENTION 
The present invention relates to improved shirred or sheated strands of 
tubular food casings and methods of manufacture. More particularly, the 
present invention relates to sausage or meat casings having improved 
end-dressings which substantially reduce or eliminate filling equipment 
jamming due to interference by residual casing material or loose tab-ends. 
Food casings, such as those made of regenerated cellulose and collagen have 
been widely used for a number of years in processing frankfurters, 
sausages, bologna, etc. For instance, the basic process for manufacturing 
small diameter casings of regenerated cellulose is known as the "viscose 
process" and is described in such patents as U.S. Pat Nos. 2,999,756 and 
3,835,113. Essentially, viscose is extruded through an annular die into a 
coagulating bath to form a tubular casing. The regenerated gel is 
impregnated with a plasticizer, dried and wound into flat reelstock. For 
convenience in handling and in filling such food casings, they are shirred 
on high-speed shirring machines, like those described in U.S. Pat. Nos. 
2,010,626; 2,583,654; 2,722,714; 2,722,715; 2,723,201; and 3,451,827. In 
the shirring process, lengths of from 40 to 200 feet of casing are 
compacted into pleated strands of a few inches, e.g., 4-30 inches at a 
rate of 10 to 15 ft./sec. 
As part of the shirring process, the strands must be severed, for example, 
from continuous reelstock from which they originated. Most of the methods 
for severing shirred artificial sausage casings routinely result in the 
formation of a loose or unshirred tab-like piece of residual casing 
material which remains at the horn insertion (tab) end of the strand. In 
the case of manual filling of sausage casings, the presence of such a 
loose tab at the horn insertion end can be rectified by the operator's 
manual dexterity and does not present a major problem. However, in 
high-speed, highly automated filling operations, the presence of a loose 
tab-end on the horn insertion end of a strand can have more major 
consequences. For example, a loose tab-end can interfere with the proper 
fitting of a strand onto the stuffing horn of a high-speed filling machine 
becoming entangled as the horn is inserted automatically into the strand. 
Under such circumstances, the strand can deshirr from both the filling and 
horn insertion end causing the process to jam, discharging meat into the 
filling station work area which means lost meat emulsion, as well as lost 
production output due to downtime. Accordingly, there is a need for 
improved tubular strands of food casings and methods of manufacture 
wherein the casings have end-dressings which eliminate jamming and fouling 
when used in conjunction with high-speed automated filling equipment. 
The present invention provides for more dependable end-dressed sausage/meat 
casings through the elimination of interfering residual casing material or 
loose tab-ends formed as by-products of shirring operations. By ironing 
down the tab-ends formed on at least one end of a severed shirred casing 
by application of heat to the terminal edge of the side-walls of a strand 
under controlled temperatures, the loose tab will cling and become an 
integral part of the casing side-wall. But, because the tab and adjacent 
casing pleats are not fused by the ironing process the casing will 
completely deshirr in a normal manner during filling operations as meat 
emulsion is forced into the strand thereby avoiding loss or waste of 
casing material. 
Accordingly, it is a principal object of the present invention to provide 
more dependable, fail-safe strands of tubular food casings which are 
compatible for use on high-speed automated filling equipment. 
It is a further object of the present invention to provide a method for 
making improved end-dressings on artificial sausage casings. 
These and other objects, features and advantages of the present invention 
will become more apparent from the following more detailed descriptions. 
SUMMARY OF THE INVENTION 
The present invention provides for improved sausage casings having an 
end-dressing on the casings' tab (horn insertion) end which will not 
impede or interfere with the normal operation of automated filling 
equipment. Pleated casings coming off shirring machinery having residual 
casing material in the form of a loose tab-end usually resulting from the 
severing of strands are dressed by compressing the residual material 
against the terminal edge of the strand while heating at a temperature 
sufficient to cause the residual material to cling to the strand without 
causing fusion or degradation of the tab or pleated casing material. The 
tab is ironed against the side-walls of the terminal edge of the strand, 
and therefore, pay-out of the strand during filling operations is not 
impeded.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Turning now to FIGS. 1 and 2, there is illustrated a strand of tubular 
casing 1, having a central opening or bore 7. The horn insertion terminal 
end of the strand has an edge 5 consisting of terminal pleats or folds of 
casing material. FIGS. 1 and 2 show the casing strand without an 
end-dressing after being severed from a longer shirred strand or flat 
reelstock, which strand may have been doffed and transferred to a strand 
handler of a shirring machine, and ready to be dressed. Hence, casing 1 
has residual casing material in the form of a loose tabend 3 remaining at 
the horn insertion terminal end as a byproduct of being separated from 
other casing material. 
The improved end-dressed shirred tubular casings and methods of manufacture 
as described herein are applicable to both edible and non-edible types. 
Typically, such casings are formed from regenerated cellulose or collagen 
of the kind used in the preparation of sausages, including frankfurters, 
etc. The concepts embodied herein are also applicable to virtually any 
shirred casing material, such as tubular films of amylose, starch, 
polyvinyl alcohol, alginates, cellulose derivatives, gelatin, casein, or 
plastic films like polystyrene, polyvinyl chloride, polyvinylidene 
chloride, polyolefins like polyethylene, polypropylene and polyesters, 
nylons, etc., whereby severing the casing material leads to the formation 
of undesired residual material at the end of the casing. In addition to 
casings having end-dressings on the tab end, i.e. the end of the strand to 
be inserted onto the stuffing horn of a filling machine, the invention 
also contemplates end-dressed strands having casing closures at the 
opposing end of the strand to prevent discharge of meat emulsion from the 
strand during filling operations. 
The objective of eliminating the problem of loose tab-end 3 from the horn 
insertion end of the strand is achieved by compressing the residual casing 
material against the terminal edge of the casing wall 5 whereby a 
dressed-end is made without obstructing the central opening 7. The 
residual material is essentially ironed to the terminal edge of the casing 
by moderate compressive force applied against that end of the strand. The 
compressive force is applied in conjunction with sufficient heat to the 
terminal edge to cause the loose tab-end to cling to the terminal pleats 
without coming apart when the compressive force is removed. Likewise, when 
the dressed-end reaches ambient temperature conditions the ironed tab will 
continue to cling to the terminal pleats, but will release from the 
terminal pleats during filling. The elevated temperatures and exposure 
time should be preferably controlled to avoid conditions which will 
produce an adhering, adhesive or sticking affect of the tab-end to the 
terminal pleats of the strand as a result of either fusion, melting or 
degrading of the casing material. A temperature sufficient to produce a 
clinging affect is most advantageous in order not to weaken the casing 
wall and avoid rupturing and loss of meat emulsion during filling 
operations. Similarly, fusion or melting of the tab-end and terminal 
pleats can impede casing pay-out during filling reducing the amount of 
casing available per strand. 
As previously indicated, the temperatures employed in making the 
end-dressing of the present invention should be controlled so as to 
produce a clinging affect. The actual temperatures utilized to achieve 
that affect are dependent on the particular casing material. Nevertheless, 
temperatures in the range of between about 150.degree. and about 
200.degree. F. were found to be suitable in a number of instances. 
However, temperatures below 150.degree. F. and above 200.degree. F. may 
also be utilized provided the exposure time is appropriately adjusted. In 
this regard, it was found at the above temperatures the exposure time will 
range from about two to about four seconds. These intervals can, of 
course, be increased by adjusting the temperature downwardly or decreased 
by increasing the temperature. Thus, for example, it is possible to form 
an end-dressing on regenerated cellulose casings at temperatures of more 
than 200.degree. F. provided the exposure time is reduced, for example, to 
two seconds or less. Accordingly, the determination of appropriate 
temperature and time intervals can be ascertained through the exercise of 
ordinary skill. 
The end-dressings of the present invention can be made, for example, 
utilizing a heating unit 11 illustrated in FIG. 6, comprising a heating 
element 13 with electrical leads 15 to an appropriate temperature control 
thermostat (not shown). Heating element 13 conducts heat to a die surface 
19 which has a inside diameter sufficient to circumscribe the edge of the 
shirred strand. The die surface may also include a rounded, convex-like 
surface centering support 17 which aids in centering and feeding the edge 
of the casing with loose tab-end 3 flush against the heated die surface 
19. Support 17 fits inside central opening 7 of casing 1 to assure 
residual casing material is ironed against the strand without protruding 
into the central opening to become entangled on the stuffing horn of a 
filling machine when inserted thereon. 
Heating unit 11 is shown equipped with a resistance-type heating element 13 
which conducts heat to die surface 19. However, the invention also 
contemplates other means for transferring heat to the edge of the casing, 
including convection and radiation means, such as by use of infra-red 
rays, forced hot air or circulating a liquid heating medium to the die, 
e.g. oil. 
The finished end-dressed casing according to the present invention is 
illustrated in FIGS. 3-5. The loose tab-end is shown ironed at 9 to the 
terminal end of the casing 1 clinging to the edge of the side-wall. The 
dressed-end 22 may have a generally glazed appearance 21. However, the 
color of the heated casing material does not vary from the balance of the 
strand indicating the absence of degradation. Correspondingly, the tabend 
and adjacent pleats can be deshirred by hand indicating the absence of any 
fusion of the tab-end to the end pleats of the strand to one another 
thereby assuring proper pay-out of the casing during filling. 
The present invention contemplates forming the end-dressings on shirred 
strands of casing by means of automated equipment. For instance, automated 
high-speed shirring machines may be equipped with a heating unit, such as 
illustrated in FIG. 6 whereby after a strand is shirred, severed, 
separated and doffed it may be transferred to a strand handler unit of a 
shirring machine which can be programmed with a cycle for compressing and 
removing the horn insertion end of the strand from the heating unit to 
form the end-dressing. Such operation can also be performed manually. 
Although the invention has been described in considerable detail with 
respect to the preferred embodiments thereof, it will be apparent that the 
invention is capable of numerous modifications and variations to those 
skilled in the art without departing from the spirit and scope of the 
invention, as defined in the appended claims.