Methods for preparing flat-bottom thermoplastic sack and systems therefore

Claim 1

A method of continuously preparing an at least substantially flat, rectangular-bottom thermoplastic film sack comprising: (a) providing a flattened gusseted tube of thermoplastic film; (b) opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; (c) forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (d) returning said gusset folds to their original position so that their seal-pairs are superimposed; (e) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams; (f) forming a pre-weakened transverse line closely adjacent and parallel to said transverse sealing seam; (g) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube; and (h) collecting the resulting structures while still interconnected at said preweakened transverse lines.

Claim 2

A method of continuously preparing an at least substantially flat, rectangular-bottom thermoplastic film sack comprising: (a) providing a flattened gusseted tube of thermoplastic film; (b) opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; (c) forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (d) returning said gusset folds to their original position so that their seal-pairs are superimposed; (e) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams; (f) forming a pre-weakened transverse line closely adjacent and parallel to said transverse sealing seam; (g) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube; and (h) collecting the resulting structures while still interconnected at said preweakened transverse lines.

Claim 12

The method of preparing an at least substantially flat rectangular bottom, thermoplastic film sack comprising; (a) providing a flattened gussetted tube of thermoplastic film; (b) opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; (c) forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent folds are at least closely spaced or in contact so as to form an angle of at least approximatly 90°; (d) returning said gusset folds to their original position so that their seal-pairs are superimposed; (e) forming a transverse sealing and severing seam across and through said collapsed tube along a line which includes the inboard ends of said pairs of diagonal seams; (f) collecting the resulting structures in a stack; (g) removing the four folded triangles of film between the diagonal sealed seams and the transverse sealing and severing seam to complete the bottom of the sack; and (h) forming handles and a sack mouth opening at the opposite end of said sack bottom.

Claim 13

The method of preparing an at least substantially flat rectangular bottom, thermoplastic film sack comprising; (a) providing a flattened gussetted tube of thermoplastic film; (b) opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; (c) forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent folds are at least closely spaced or in contact so as to form an angle of at least approximatly 90°; (d) returning said gusset folds to their original position so that their seal-pairs are superimposed; (e) forming a transverse sealing and severing seam across and through said collapsed tube along a line which includes the inboard ends of said pairs of diagonal seams; (f) collecting the resulting structures in a stack; (g) removing the four folded triangles of film between the diagonal sealed seams and the transverse sealing and severing seam to complete the bottom of the sack; and (h) forming handles and a sack mouth opening at the opposite end of said sack bottom.

Claim 17

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic bag comprising: (a) forming a tube of thermoplastic film; (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel, gussets; (c) opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or contact so as to form an angle of at least 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneously severing said collapsed tube along a line closely adjacent to said transverse sealed seams; (g) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube.

Claim 18

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic bag comprising: (a) forming a tube of thermoplastic film; (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel, gussets; (c) opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or contact so as to form an angle of at least 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneously severing said collapsed tube along a line closely adjacent to said transverse sealed seams; (g) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube.

Claim 22

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising: (a) forming a tube of thermoplastic film; (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel gussets; (c) opening simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneouly forming a preweakened transverse line closely adjacent and parallel to said transverse sealed seam; (g) collecting the resulting structure in a stack so that all of said diagonal seams are at one end of said stack; and (h) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube.

Claim 23

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising: (a) forming a tube of thermoplastic film; (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel gussets; (c) opening simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneouly forming a preweakened transverse line closely adjacent and parallel to said transverse sealed seam; (g) collecting the resulting structure in a stack so that all of said diagonal seams are at one end of said stack; and (h) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube.

Claim 26

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising: (a) forming a tube of thermoplastic film (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel gussets; (c) opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneously forming a preweakened transverse line closely adjacent and parallel to said transverse sealed seam and a second transverse sealed seam across said tube closely adjacent and parallel to said preweakened line; (g) collecting the resulting structure in a stack so that all of said diagonal seams are at one end of said stack; and (h) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube; and (i) forming a handle and sack mouth opening at the opposite end of said sack bottom.

Claim 27

A method of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising: (a) forming a tube of thermoplastic film (b) collapsing said tube while simultaneously forming therein two oppositely disposed, parallel gussets; (c) opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full lay-flat extent; (d) simultaneously or spatially sequentially forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and simultaneously forming a preweakened transverse line closely adjacent and parallel to said transverse sealed seam and a second transverse sealed seam across said tube closely adjacent and parallel to said preweakened line; (g) collecting the resulting structure in a stack so that all of said diagonal seams are at one end of said stack; and (h) removing the four double film triangular regions bounded by said diagonal seams, said transverse seam and the side edges of said tube; and (i) forming a handle and sack mouth opening at the opposite end of said sack bottom.

Claim 28

A system for preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising in combination: (a) means for forming a tube of thermoplastic film; (b) means for collapsing said tube including means for simultaneously forming therein two oppositely disposed, parallel, gussets; (c) means for opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full, lay-flat extent; (d) means for simultaneously or spatially sequentially forming in each of the four gusset folds a diagonal seam over the portion of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) means for returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) means for forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and means for simultaneously forming a pre-weakened transverse line closely adjacent and parallel to said transverse sealed seams; (g) means for removing four double film triangular regions bounded by said diagonal seams said transverse seam and the side edges of said tube; and (h) means for collecting the resulting structures while still interconnected at said pre-weakened transverse lines.

Claim 29

A system for preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising in combination: (a) means for forming a tube of thermoplastic film; (b) means for collapsing said tube including means for simultaneously forming therein two oppositely disposed, parallel, gussets; (c) means for opening, simultaneously or spatially sequentially, a gusset fold on each side of said collapsed tube to their full, lay-flat extent; (d) means for simultaneously or spatially sequentially forming in each of the four gusset folds a diagonal seam over the portion of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (e) means for returning said gusset folds to their original position so that their seal-pairs are superimposed; (f) means for forming a transverse sealed seam across said tube along a line which includes the inboard ends of said pairs of diagonal seams and means for simultaneously forming a pre-weakened transverse line closely adjacent and parallel to said transverse sealed seams; (g) means for removing four double film triangular regions bounded by said diagonal seams said transverse seam and the side edges of said tube; and (h) means for collecting the resulting structures while still interconnected at said pre-weakened transverse lines.

Claim 36

A system of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising in combination: (a) means for providing a collapsed gusseted tube of thermoplastic film; (b) means for opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; means for forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (c) means for returning said gusset folds to their original position so that their seal-pairs are superimposed; (d) means for forming a transverse sealing and severing seam across and through said collapsed tube along a line which includes the inboard ends of said pairs of diagonal seams; (e) means for collecting the resulting structures in a stack; (f) means for removing the four folded triangles of film between the diagonal sealed seams and the transverse sealing and severing seam to complete the bottom of the sack; and (g) means for forming a pair of handles and a sack mouth opening at the opposite end of said sack bottom.

Claim 37

A system of continuously preparing an at least substantially flat, rectangular-bottom, thermoplastic film sack comprising in combination: (a) means for providing a collapsed gusseted tube of thermoplastic film; (b) means for opening a gusset fold on each side of said collapsed tube to their full lay-flat extent; means for forming in each of the four gusset folds, a diagonal sealed seam over the portions of the tube width corresponding to the gussets along lines diagonal to the length of the tube so that the ends of the sealed seams of adjacent gusset folds are at least closely spaced or in contact so as to form an angle of at least approximately 90°; (c) means for returning said gusset folds to their original position so that their seal-pairs are superimposed; (d) means for forming a transverse sealing and severing seam across and through said collapsed tube along a line which includes the inboard ends of said pairs of diagonal seams; (e) means for collecting the resulting structures in a stack; (f) means for removing the four folded triangles of film between the diagonal sealed seams and the transverse sealing and severing seam to complete the bottom of the sack; and (g) means for forming a pair of handles and a sack mouth opening at the opposite end of said sack bottom.