A bag for free flowing powders or granules has a cylindrical body portion of a bag proper, top and bottom end portion which close top and bottom openings of the bag proper, and a cylindrical filling portion formed on the top end portion. Top edges of the cylindrical bag proper are sewn along a line passing through a point of a central axis of the cylindrical filling portion. The above-mentioned bag is made from a sheet-like cloth or a tube fabric.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to bags for use in storing and transporting 
bulk materials, such as free-flowing powders and granules, farms produce 
and such like and a process for manufacturing such bags. More 
particularly, the present invention relates to an improved bag having a 
material filling opening formed in the top portion thereof and a process 
for manufacturing this bag. 
(2) Description of the Prior Art 
In known bags having an opening for filling, formed in the top portion 
thereof, the filling opening and a top end cover are separately formed and 
sewn together, and the top end cover is then sewn to a bag proper. 
Accordingly, known bags have the defect that the sewing operation thereof 
is very troublesome and the efficiency of the sewing operation is very 
low. 
Furthermore, the top end cover of the known bag is sewn to the bag proper 
along the entire length thereof to form a seam. As a result, the known 
bags have an additional defect in that this seam can be broken or loosened 
by an impact or shock imposed during the operation of piling or loading 
the bags for storage or transportation. Accordingly, from the viewpoint of 
carrying out the piling and loading operations without encountering this 
defect, it has been desired to improve the quality of these bags. 
SUMMARY OF THE INVENTION 
It is a primary object of the present invention to provide a practical bag 
in which the above-mentioned defects involved in the conventional bags are 
eliminated and an economical process for manufacturing such a bag. 
In accordance with the present invention, there is provided a bag for use 
in storing and transporting a bulk material, having a cylindrical body 
portion of the bag proper, top and bottom end portions which close top and 
bottom openings of said bag proper, a cylindrical portion providing an 
opening for filling the bag and formed in the central portion of said top 
end portion, a plurality of hanging slings sewn to said bag body portion 
at predetermined positions adjacent to said top end portion, wherein said 
top end portion is formed integrally with said bag proper and sutured by a 
seam formed along a line passing through a central line in the 
longitudinal direction of said bag. The cylindrical portion for filling 
material may be formed of a material different from the material of the 
bag proper and sewn to the top end cover at the center thereof. 
Another aspect the present invention provides a process for manufacturing a 
bag comprising a cylindrical body portion of the bag proper, top end and 
bottom end portions which close top and bottom openings of said bag 
proper, a cylindrical portion providing an opening for filling material 
formed in the central portion of said top end portion, comprising a first 
step of creating a cylindrical body corresponding to said bag proper 
provided with a pair of upper projections, having an identical shape and 
dimensions, projected from the upper edge portion thereof at two 
symmetrical positions with regard to the central axis of said cylindrical 
body, a second step of closing a bottom opening of said cylindrical body 
with said bottom end cover by sewing it to the bottom edge of said 
cylindrical body, a third step of superimposing said upper projections 
whereby said upper edge portion of said cylindrical body is divided into 
two edge portions capable of being superimposed on each other so that two 
L-shaped superimposed edge portions are symmetrically created with respect 
to the longitudinal center line of said superimposed upper projections, a 
fourth step of sewing said pair of L-shaped superimposed edge portions. 
Accordingly, in preparing a bag according to the present invention, the 
sewing operation is conducted only for connecting the edge of the top end 
portion to the material charging cylindrical portion formed by cutting off 
the excess portions along L-shaped lines. Therefore, the sewing operation 
is simplified and is performed at a high efficiency compared with that of 
the known bags. Furthermore, in this case, since the portion for filling 
is formed integrally with the bag proper, the operation of charging a 
material into the bag from a top filling opening of the charging 
cylindrical portion can be performed very smoothly and the final bag is 
excellent in its adaptability to the charging operation. 
The above described process for the preparation of bags may be applied not 
only to the above-mentioned case where a sheet-like fabric material is 
used but also to the case where a tubular woven fabric forward by a 
circular loom or the like is used as the starting fabric material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
For the sake of a better understanding the present invention, a known bag 
for transporting powder, granules, etc., will first be described before 
the present invention is explained. 
As illustrated in FIG. 1, a conventional bag comprises a bag proper 1 
having a cylindrical form when a bulk material is filled therein, end 
portions in the top and bottom (not illustrated in FIG. 1), and a 
cylindrical portion 3 for filling material formed in the central portion 
of the top end portion 2 of the bag proper 1. The top end portion 2 is 
sewn to the cylindrical bag proper 1 along the circular edge thereof, and 
the cylindrical portion 3 is sewn to the top end portion 2 as illustrated 
in FIG. 1. Accordingly, as pointed out hereinbefore, these seams formed by 
such sewing operation, especially the seam between the top end portion 2 
and the cylindrical bag proper 1, are poor in strength, and problems of 
breaking and loosening of the seams arise owing to their insufficient 
strength when the bag is put into practical use. Moreover, the 
manufacturing process is intricate because of the required complicated 
sewing operation, and this results in a low efficiency of the sewing 
operation and a high manufacturing cost. Elimination of these defects has 
been strongly desired in the art. 
The bag of the present invention, will now be described in detail with 
reference to the embodiments illustrated in the accompanying drawings. 
The bag of the present invention, illustrated in FIGS. 2, 3 and 4, 
comprises a cylindrical bag proper 4, a bottom end portion 5 sewn to the 
bottom of the bag proper 4 along a seam 5a and four hanging slings 8 
mounted at symmetrical positions on the upper side-face of the bag proper 
4. In the top portion of the bag proper 4, a cylindrical portion 6 for 
filling the bag with material is formed integrally with the bag proper 4 
around the central line Z--Z(axis) in the longitudinal direction of the 
bag, and the cylindrical portion 6 is sewn through seams 7a and 7b, so 
that a top end portion 7 is formed integrally with the bag proper 4. The 
seams 7a and 7b are located symmetrically with each other with respect to 
the central line Z--Z(axis) in the longitudinal direction of the bag 
proper 4. In the embodiment illustrated in FIGS. 2, 3 and 4, a reinforcing 
effect is attained by folding inwardly selvages 4a and 4b of the bag 
proper 4, and sewing them to the corresponding seams 7a and 7b through 
seams 4c and 4d, respectively. 
In the embodiment illustrated in FIGS. 2, 3 and 4, the bottom end portion 5 
is sewn to the bag proper 4. According to experiments conducted by the 
inventors of the present invention, the bottom portion of the bag with the 
above-mentioned seam has a sufficient strength with regard to any expected 
forces which would be imparted to this portion during practical use. 
Therefore, the remaining problem to attain the purpose of the present 
invention concerns the construction of the top end portion 7. If a 
sufficient reinforcing effect can be created in this top end portion 7, 
there can be provided a bag having good strength which is sufficient to 
resist various operations. In this regard, since the top end portion 7 is 
integrated with the bag proper 4 through the seams 7a and 7b, which are 
symmetrical with each other with respect to the center of the top end 
portion 7, the top end portion 7 has much greater strength than the top 
end portion of the conventional bag illustrated in FIG. 1. Moreover, since 
the selvages 4a and 4b are inwardly folded and sewn to the seams 7a and 
7b, the strength of the top end portion 7 is further increased. 
In the above-mentioned embodiment, after a bulk material has been filled in 
the bag, the cylindrical portion 6 is closed by means of a tying tape 9 
around the cylindrical portion 6. 
As illustrated in FIGS. 3, 4 and 5, the hanging sling 8 adopted in the 
above-mentioned embodiment comprises a base 8b sewn to the bag proper 4 
through a seam 10 at the above-mentioned predetermined position adjacent 
to the top end portion 7 of the bag proper 4 and an upper loopy hanging 
portion 8a. The base 8b has an appropriate length extending along the 
central line in the longitudinal direction of the bag proper 4 toward the 
bottom end portion 5. From the viewpoint of the strength of the bag, the 
length of the base 8b of the hanging sling 8 need not always be such that 
the base 8b is extended to the bottom end portion 5. This hanging sling 8 
is disclosed in detail in Japanese Utility Model Application Laid-Open 
Specification No. 50670/78. Accordingly, a detailed explanation of the 
hanging sling is omitted here. 
FIGS. 6 and 7 illustrate a process for manufacturing a bag of the present 
invention from one sheet-like fabric material. According to the process 
illustrated in FIGS. 6 and 7, a bag can be made very efficiently by 
carrying out the following steps of cutting a starting fabric, attaching 
hanging slings and sewing the fabric into a bag. 
(a) A starting fabric is cut to make a cut material provided with a shape 
and dimensions which are identical to a piece of fabric made by the 
following operation. 
A bag is cut along the line IX--IX in FIG. 4, and the resulting two unit 
fabrics, exclusive of a portion corresponding to the bottom end portion 5, 
are connected, so as to create a one piece fabric as illustrated in FIG. 
6. Therefore, the connecting line of the above-mentioned two unit fabrics 
corresponds to the line X--X in FIG. 6. The cut material has a shape and 
dimensions which are identical to the above-mentioned one piece of fabric 
illustrated in FIG. 6. As illustrated in FIG. 6, the left and right unit 
fabrics 4g are symmetrical with each other with respect to the line X--X. 
Moreover, each of the unit fabrics 4g is symmetrical with respect to the 
central line Y--Y in the longitudinal direction. A projecting portion 6a, 
for forming the cylindrical portion 6 (see FIGS. 3 and 4) for filling the 
bag with a bulk material, is formed integrally with each unit fabric 4g 
above the upper edge 4h of the unit fabric 4g, corresponding to the bag 
proper 4 of the bag, by the cutting operation. 
(b) Then, four hanging slings 8 are sewn to predetermined positions of the 
unit fabrics 4g. As pointed out hereinbefore, these predetermined 
positions are symmetrical with respect to the central line in the 
longitudinal direction of the bag in the sewn and completed state as 
illustrated in FIG. 4. At this step, a tying tape 9 is sewn to the side 
edge of one projecting portion 6a. 
(c) The unit fabrics 4g are folded along the line X--X as illustrated in 
FIG. 7 and both side edges 4e are superimposed with each other and sewn 
together along a seam 4l (FIG. 7) to form a bag proper 4 having a 
cylindrical shape. 
(d) The bottom of the bag proper 4 is tightly sewn to a bottom end portion 
5 having a square shape (in the embodiment illustrated in FIGS. 3 and 4), 
along a seam 5a to form a bottom portion of the bag. 
(e) Then, the superimposed upper edges of the body portions 4g and the 
superimposed side edges 6b of the projecting portions 6a are sewn together 
along seams 7a and 7b and seams 6c and 6d, respectively, to form an 
opening 6e for filling the bag with material as a top opening of the 
cylindrical portion 6. 
A bag as illustrated in FIGS. 3 and 4 is made by the above-mentioned 
cutting and sewing operations. As pointed out hereinbefore, according to 
this manufacturing process, the top end portion 7 of the bag can be formed 
very simply and assuredly. 
In the above-mentioned embodiment, the projecting portions 6a and body 
portions 4g are integrally cut from one sheet-like fabric material. In the 
present invention, the projecting portions may be formed of a material 
softer than the material of the body portions 4g. In this case, the 
operation of closing the opening of the cylindrical portion for filling 
bulk material by a tape 9, after filling of a bulk material, can be 
facilitated. Accordingly, an embodiment in which a projecting portion 6a 
formed of a material different from the material of the body portion 4g is 
sewn to the body portion 4g along a line 4i, connecting the upper edges of 
the body portion 4g is included in the scope of the present invention, and 
the intended object of the present invention can also be attained 
effectively by this embodiment. More specifically, is this embodiment 
rectangular body portions 4g (see FIG. 6) are cut from a first material 
for the bag proper, and projecting portions 6a are cut from a second 
material. These portions 4g and 6a are then sewn along imaginary lines 4i 
to obtain a cut fabric with substantially the same shape as the cut fabric 
shown in FIG. 6. Accordingly, if the sewing operation is then carried out 
according to the process explained hereinbefore with reference to FIGS. 6 
and 7, an intended bag can be formed. 
In each of the above-mentioned embodiments of the process for manufacturing 
the bags according to the present invention, a sheet-like fabric material 
is employed as the starting material. If a tubular woven fabric or 
cylindrical material is used as the starting material for production of 
bags, the preparation process is further simplified, and since there is no 
seam extending in the lengthwise direction in the bag proper 44 of the 
resulting bag, the strength of the resulting bag is further improved. In 
such a case, the following process is effective for attaining the object 
of the present invention. 
A tubular woven fabric or cylindrical material, such as a laminated tubular 
woven fabric or synthetic resin tube, having the same circumferential 
dimension as that of the body portion of the desired bag, is prepared. The 
fabric or material is flattened into a similar condition to that wherein 
two sheet-like material pieces are superimposed on each other. Then, the 
flattened material is cut in a shape resembling the shape of the body 
portion 4g illustrated in FIG. 6. More specifically, the cylindrical 
material is cut to a length corresponding to the length of the unit sheet 
fabric along the line Y--Y and, as indicated in FIG. 6, the excess upper 
portions on both the sides of the top end cover are cut off along L-shaped 
lines while leaving the portion corresponding to the upper cylindrical 
portion for filling the bulk material. Then, the sewing operation is 
carried out so as to form the top end portion and the upper cylindrical 
portion for filling material in the same manner as described hereinbefore 
with respect to the first embodiment, whereby an intended bag can be 
prepared very efficiently. In this embodiment, the operation of sewing the 
hanging slings 8 to the bag proper 4 is performed prior to formation of 
seams 7a, 7b, 6c and 6d. 
The material constituting the bag of the present invention is appropriately 
chosen depending on the kind of a bulk material to be charged. Ordinarily, 
sheet-like plain woven fabric and tubular woven fabrics composed of flat 
yarns of a synthetic resin, such as polyethylene or polypropylene, or 
products obtained by laminating these fabrics with a synthetic rubber or 
resin are preferably employed. Moreover, a cylindrical film of a synthetic 
resin can be used. 
As will be apparent from the above-descriptions, the most characteristic 
feature of the present invention resides in the manufacturing process, in 
that since a cylindrical portion is projected upwardly from the bag proper 
and the top opening of this cylindrical portion is used as an opening for 
filling a bulk material, excess portions corresponding to the portions on 
both the sides of this cylindrical portion above the top end portion are 
cut off along L-shaped lines from the material-fabric and the remaining 
portion is sewn so that the edge of the top end portion is formed. By 
virtue of this characteristic feature, in the present invention, the 
cylindrical portion provided with an opening for filling a bulk material 
and the top end portion are formed integrally with the bag proper, and the 
sewing operation can be remarkably simplified because sewing of the entire 
circumference of the top end portion with the bag proper, which is 
indispensable in the conventional technique, can be omitted. 
Accordingly, the strength of the bag of the present invention is much 
higher than the strength of the conventional bags, and therefore, the bag 
of the present invention is very advantageous in that accidents due to the 
breaking or splitting of the bag can be effectively eliminated. Moreover, 
since the cylindrical portion provided with an opening for filling a bulk 
material is integrally formed with the bag proper, the bag of the present 
invention has a very good shape-retaining property and the operation of 
filling a bulk material therein can be performed very smoothly. These are 
the prominent advantages attained by at least preferred embodiments of the 
present invention.