Method of extruding tubing for fastener bags

Claim 1

The method of making a continuous plastic tube with fastener profiles on the surface thereof for use in making reclosable bags comprising: extruding a heated thermoplastic material from a die through an annular die slot and thereby forming a tube and concurrently extruding plastic through shaped die profile openings aligned with said die slot and thereby forming mating complementary interlocking rib and groove fastener profiles on the tube surface, supplying tube plastic to the annular slot through a tube passage, supplying profile plastic to said fastener profile die openings through a profile passage, supplying gas into the tube emerging from the die slot to circumferentially control the size of the plastic tube, controllably varying the rate of plastic supply to the annular slot by increasing or decreasing the speed at which plastic material is forced through the tube passage to the slot to thereby vary the rate at which the tube is extruded, controllably varying the flow of the gas into the tube relative to the rate of plastic supply to control the increase in tube diameter and to obtain a tube of a predetermined wall thickness and tubing diameter, and controllably varying by adjustment the rate of plastic supply to said profile openings by restricting the flow of plastic supply through the profile passage so as to supply a tube with controlled variation in diameter and thickness with said profiles thereon of constant and optimum dimensions.

Claim 2

The method of making a continuous plastic tube with fastener profiles on the surface thereof for use in making reclosable bags comprising: extruding a heated thermoplastic material from a die through an annular die slot and thereby forming a tube and concurrently extruding plastic through shaped die profile openings aligned with said die slot and thereby forming mating complementary interlocking rib and groove fastener profiles on the tube surface, supplying tube plastic to the annular slot through a tube passage, supplying profile plastic to said fastener profile die openings through a profile passage, supplying gas into the tube emerging from the die slot to circumferentially control the size of the plastic tube, controllably varying the rate of plastic supply to the annular slot by increasing or decreasing the speed at which plastic material is forced through the tube passage to the slot to thereby vary the rate at which the tube is extruded, controllably varying the flow of the gas into the tube relative to the rate of plastic supply to control the increase in tube diameter and to obtain a tube of a predetermined wall thickness and tubing diameter, and controllably varying by adjustment the rate of plastic supply to said profile openings by restricting the flow of plastic supply through the profile passage so as to supply a tube with controlled variation in diameter and thickness with said profiles thereon of constant and optimum dimensions.

Claim 13

The method of making a continuous plastic tube with small critically sized complementary interlocking fastener profiles thereon for use in making reclosable bags, comprising: extruding a heated thermoplastic material from a die through an annular die slot and thereby forming a tube and concurrently extruding plastic through shaped small critically sized die profile openings and aligned with the slot and thereby forming mating complementary rib and groove fastener profiles on the tube surface; supplying tube plastic to the annular slot; supplying profile plastic to said fastener profile die openings; supplying gas into the tube emerging from the die slot to circumferentially control the size of the plastic tube; controllably varying by a first control means the rate of flow of plastic supply to the annular slot; controllably varying by a second control means the rate of flow of profile forming plastic to the shaped profile openings until a small critically sized profile is extruded from said openings; controllably varying by a third control means the flow of gas to control the diameter of the tube; and changing said second control means as a function of the change of the first and third means so that as said first and third means are changed to obtain a tube of different dimensions the second means is changed to maintain the size of profile constant to said critical size.

Claim 14

The method of making a continuous plastic tube with small critically sized complementary interlocking fastener profiles thereon for use in making reclosable bags, comprising: extruding a heated thermoplastic material from a die through an annular die slot and thereby forming a tube and concurrently extruding plastic through shaped small critically sized die profile openings and aligned with the slot and thereby forming mating complementary rib and groove fastener profiles on the tube surface; supplying tube plastic to the annular slot; supplying profile plastic to said fastener profile die openings; supplying gas into the tube emerging from the die slot to circumferentially control the size of the plastic tube; controllably varying by a first control means the rate of flow of plastic supply to the annular slot; controllably varying by a second control means the rate of flow of profile forming plastic to the shaped profile openings until a small critically sized profile is extruded from said openings; controllably varying by a third control means the flow of gas to control the diameter of the tube; and changing said second control means as a function of the change of the first and third means so that as said first and third means are changed to obtain a tube of different dimensions the second means is changed to maintain the size of profile constant to said critical size.