Shoe sewing process method

Abstract

The invention belongs to the technical field of shoe sewing processes, and provides a shoe sewing process method which comprises the following steps: (1) preliminarily fixing a vamp and a lining through ultrasonic welding; (2) performing double-thread lock sewing on the edges of the vamp and the lining by adopting a double-needle sewing machine, and controlling the thread tension to be 5-8N and the stitch length to be 2-3mm; (3) coating a hot melt adhesive on a suture part, and infiltrating the hot melt adhesive into a suture gap through infrared heating; (4) applying pressure of 0.5-1.2 MPa to the combined part of the vamp and the sole by using mould pressing equipment, and keeping the temperature at 80-100 DEG C for 10-15 minutes; and (5) trimming redundant thread residues after cooling and shaping, and carrying out waterproof coating treatment. Through combination of double-thread lock sewing and hot melt adhesive permeation, the problem of thread opening is effectively avoided. The shoe sole and the vamp are combined to be more fit with the foot shape through sectional type pressurizing and curing, the traditional gluing and fixing time is shortened, and the whole process period is shortened by 25%-30%.

Description

Technical Field

[0001] The invention relates to the technical field of shoe sewing technology, in particular to a shoe sewing technology method. Background Art

[0002] Traditional footwear sewing processes mostly use manual or single-thread sewing machines combined with adhesive fixation, which has the following technical defects: 1. Insufficient structural stability: The stitches of single-thread sewing are prone to unraveling due to uneven tension or wear, and traditional adhesives are prone to brittleness after curing, and the bonding between the stitches and the adhesive layer is poor. After long-term use, the upper and lining are easy to peel off. 2. Low production efficiency: Manual sewing and gluing are time-consuming step-by-step operations, and the adhesive requires a long time to naturally cure, which is difficult to adapt to large-scale production needs. 3. Poor environmental protection: Solvent-based adhesives (such as chloroprene rubber) release volatile organic compounds (VOCs) during the production process and do not meet green manufacturing standards. Waterproof and comfort limitations: Conventional stitching lacks effective sealing, and rainwater can easily penetrate through pinholes; equal pressure molding is used when curing the sole and upper, resulting in local loose fit, affecting wearing comfort.

[0003] In recent years, some improved processes have tried to introduce ultrasonic welding or hot melt adhesive technology, but the following problems still exist: ultrasonic welding is only used for local fixation and does not form a synergistic enhancement effect with the sewing process; hot melt adhesive has insufficient permeability and is difficult to fill the gaps in the seams, resulting in limited improvement in waterproofness and bonding strength; the curing process parameters (such as pressure and temperature) are not differentiated for different parts of the shoe body (such as the toe and heel), which is prone to stress concentration or deformation. Based on this, it is urgent to develop an efficient, environmentally friendly shoe sewing process method that takes into account both structural strength and comfort. Summary of the invention

[0004] The purpose of the present invention is to provide a shoe sewing process method which is efficient, environmentally friendly and can take into account both structural strength and comfort, so as to overcome the defects of the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a shoe sewing process method, comprising the following steps:

[0007] (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding;

[0008] (2) Double-thread lockstitching: Use a double-needle sewing machine to double-thread lockstitch the edges of the upper and lining. The thread tension is controlled at 5-8N and the stitch length is 2-3mm;

[0009] (3) Hot melt adhesive bonding: Apply hot melt adhesive to the suture area and use infrared heating to make the adhesive penetrate into the suture gap;

[0010] (4) Pressurized curing: Use a molding device to apply a pressure of 0.5-1.2 MPa to the joint between the upper and the sole, and maintain the temperature at 80-100°C for 10-15 minutes;

[0011] (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating.

[0012] Preferably, the double-thread lockstitching in step (2) is made of high-tenacity polyester blended thread with a thread diameter of 0.2-0.3 mm, and the inner and outer sutures are in a cross-mesh structure.

[0013] Preferably, the hot melt adhesive in step (3) is a polyurethane-based environmentally friendly adhesive with a melting temperature of 120-140° C. and a coating thickness of 0.1-0.3 mm.

[0014] Preferably, the molding equipment in step (4) is a segmented air pressure mold, and the pressure at the toe and heel area is 10%-15% higher than that at the middle area.

[0015] Preferably, the waterproof coating in step (5) is a fluorine-containing resin material, the spraying amount is 5-8g / double, and after curing, a micron-level hydrophobic film layer is formed.

[0016] Beneficial effects:

[0017] 1. Improved structural strength: Through the combination of double-thread lock stitching and hot melt adhesive penetration, the peel strength of the stitching area is increased by 40%-50%, effectively avoiding the problem of open thread.

[0018] 2. Comfort and durability: Segmented pressurized curing makes the sole and upper fit the foot shape better, while the hydrophobic coating extends the service life of the shoe.

[0019] 3. Optimization of production efficiency: Ultrasonic welding reduces the time of traditional adhesive fixing and shortens the overall process cycle by 25%-30%.

[0020] 4. Environmental protection: The use of solvent-free polyurethane adhesive and fluorine-containing resin coating reduces VOC emissions and meets green manufacturing standards. At the same time, the double-thread sewing process reduces the rework rate and the waste rate by 15%-20%. DETAILED DESCRIPTION

[0021] The present invention provides a shoe sewing process method, which is characterized by comprising the following steps:

[0022] (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding;

[0023] (2) Double-thread lockstitching: Use a double-needle sewing machine to double-thread lockstitch the edges of the upper and lining. The thread tension is controlled at 5-8N and the stitch length is 2-3mm;

[0024] (3) Hot melt adhesive bonding: Apply hot melt adhesive to the suture area and use infrared heating to make the adhesive penetrate into the suture gap;

[0025] (4) Pressurized curing: Use a molding device to apply a pressure of 0.5-1.2 MPa to the joint between the upper and the sole, and maintain the temperature at 80-100°C for 10-15 minutes;

[0026] (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating.

[0027] In the present invention, the double-thread lock stitching in step (2) is made of high-tenacity polyester blended thread with a thread diameter of 0.2-0.3 mm, and the inner and outer stitches are in a cross-net structure.

[0028] In the present invention, the hot melt adhesive in step (3) is a polyurethane-based environmentally friendly adhesive with a melting temperature of 120-140° C. and a coating thickness of 0.1-0.3 mm.

[0029] In the present invention, the molding equipment in step (4) is a segmented air pressure mold, and the pressure at the toe and heel area is 10%-15% higher than that at the middle area.

[0030] In the present invention, the waterproof coating in step (5) is a fluorine-containing resin material, the spraying amount is 5-8g / double, and after curing, a micron-level hydrophobic film layer is formed.

[0031] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0032] Example 1

[0033] A shoe sewing process method comprises the following steps:

[0034] (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding;

[0035] (2) Double-thread lockstitching: A double-needle sewing machine is used to double-thread lockstitch the edges of the upper and the lining. The thread tension is controlled at 5N and the stitch length is 2mm. The double-thread lockstitching thread is made of high-tenacity polyester blended thread with a thread diameter of 0.2mm, and the inner and outer stitches are in a cross-mesh structure.

[0036] (3) Hot melt adhesive bonding: Apply hot melt adhesive to the seam area and use infrared heating to allow the adhesive to penetrate into the seam gap; the hot melt adhesive is a polyurethane-based environmentally friendly adhesive with a melting temperature of 120°C and a coating thickness of 0.1 mm.

[0037] (4) Pressurized curing: Use a molding device to apply a pressure of 0.6 MPa to the joint between the upper and the sole, and maintain the temperature at 80°C for 11 minutes; the molding device is a segmented air pressure mold, and the pressure at the toe and heel is 10% higher than that in the middle area.

[0038] (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating. The waterproof coating is a fluorine-containing resin material with a spraying amount of 5g / double. After curing, a micron-level hydrophobic film layer is formed.

[0039] Example 2

[0040] A shoe sewing process method comprises the following steps:

[0041] (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding;

[0042] (2) Double-thread lockstitching: A double-needle sewing machine is used to double-thread lockstitch the edges of the upper and the lining. The thread tension is controlled at 7N and the stitch length is 3mm. The double-thread lockstitching thread is made of high-tenacity polyester blended thread with a thread diameter of 0.3mm, and the inner and outer stitches are in a cross-mesh structure.

[0043] (3) Hot melt adhesive bonding: Apply hot melt adhesive to the seam area and use infrared heating to allow the adhesive to penetrate into the seam gap; the hot melt adhesive is a polyurethane-based environmentally friendly adhesive with a melting temperature of 130°C and a coating thickness of 0.2 mm.

[0044] (4) Pressurized curing: Use a molding device to apply a pressure of 1.0 MPa to the joint between the upper and the sole, and maintain the temperature at 90°C for 13 minutes; the molding device is a segmented air pressure mold, and the pressure at the toe and heel is 13% higher than that in the middle area.

[0045] (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating. The waterproof coating is a fluorine-containing resin material with a spraying amount of 7g / double. After curing, a micron-level hydrophobic film layer is formed.

[0046] Example 3

[0047] A shoe sewing process method comprises the following steps:

[0048] (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding;

[0049] (2) Double-thread lockstitching: A double-needle sewing machine is used to double-thread lockstitch the edges of the upper and the lining. The thread tension is controlled at 8N and the stitch length is 3mm. The double-thread lockstitching thread is made of high-tenacity polyester blended thread with a thread diameter of 0.3mm, and the inner and outer stitches are in a cross-mesh structure.

[0050] (3) Hot melt adhesive bonding: Apply hot melt adhesive to the seam area and use infrared heating to allow the adhesive to penetrate into the seam gap; the hot melt adhesive is a polyurethane-based environmentally friendly adhesive with a melting temperature of 140°C and a coating thickness of 0.3 mm.

[0051] (4) Pressurized curing: Use a molding device to apply a pressure of 1.2 MPa to the joint between the upper and the sole, and maintain the temperature at 100°C for 15 minutes; the molding device is a segmented air pressure mold, and the pressure at the toe and heel is 15% higher than that in the middle area.

[0052] (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating. The waterproof coating is a fluorine-containing resin material with a spraying amount of 8g / double. After curing, a micron-level hydrophobic film layer is formed.

[0053] Performance test: Table 1 is the test of the peel strength of the stitching part, and the standard GB / T3903.31-2019 footwear peel strength test is implemented; Table 2 is the SEM observation of the colloid penetration depth and the integrity of the bonding interface; Table 3 is the sole-upper bonding strength test, and the standard ISO17707:2018 footwear anti-delamination strength is implemented; Table 4 is the environmental protection and production efficiency data.

[0054] Table 1 Double-thread lockstitch process performance verification

[0055] Group Suture Type <![CDATA[Peeling strength (N / cm )]]> Open wire rate (after 100 bends) Example 1 Double cross-stitching 58.2±2.1 2％ Example 2 Double cross-stitching 59.2±2.1 2％ Example 3 Double cross-stitching 59.6±2.1 1％ Comparative Example 1 Single-thread flat seam 38.5±1.8 18％ Comparative Example 2 Double parallel lock seam 49.6±1.9 8％

[0056] Table 2 Analysis of hot melt adhesive penetration effect

[0057] Penetration depth (μm) Shear strength(MPa) Example 1 85±10 3.2±0.3 Example 2 150±15 4.8±0.4 Example 3 210±20 5.1±0.5

[0058] Table 3 Effect of segmented pressurization curing

[0059]

[0060] Table 4 Environmental protection and production efficiency data

[0061]

[0062] It can be seen from the above embodiments that the present invention provides a method for sewing shoes. As shown in Table 1, the cross-mesh double-line lockstitching of embodiments 1 to 3 increases the peeling strength by 50.4% compared with the single-line traditional process of the comparative example, and the open line rate is reduced to 1 / 9 of the traditional process. As shown in Table 2, compared with the traditional sewing without colloid penetration, when the colloid thickness is 0.2-0.3mm and heated at 130-140°C, the penetration depth reaches more than 150μm, and the shear strength is increased by 52%. As shown in Table 3, after the toe / heel pressure of the embodiment (segmented pressurization) is increased by 10-15%, the bonding strength is increased by 35.2%, and the delamination problem is completely eliminated. As shown in Table 4, the cycle of embodiments 1 to 3 is shortened by 26.7% compared with the traditional process, VOC emissions are reduced by 76%, and the scrap rate is reduced by 33.8%.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A shoe sewing process, characterized in that: The following steps are involved: (1) Pretreatment: The upper and lining are initially fixed by ultrasonic welding; (2) Double-thread lockstitching: Use a double-needle sewing machine to double-thread lockstitch the edges of the upper and lining. The thread tension is controlled at 5-8N and the stitch length is 2-3mm; (3) Hot melt adhesive bonding: Apply hot melt adhesive to the suture area and use infrared heating to make the adhesive penetrate into the suture gap; (4) Pressurized curing: Use a molding device to apply a pressure of 0.5-1.2 MPa to the joint between the upper and the sole, and maintain the temperature at 80-100°C for 10-15 minutes; (5) Post-processing: After cooling and shaping, trim the excess thread ends and apply waterproof coating.

2. The sewing process according to claim 1, characterized in that: The double-thread lock stitching in step (2) is made of high-tenacity polyester blended thread with a thread diameter of 0.2-0.3 mm, and the inner and outer stitches are in a cross-net structure.

3. The sewing process according to claim 1, characterized in that: The hot melt adhesive in step (3) is a polyurethane-based environmentally friendly adhesive with a melting temperature of 120-140° C. and a coating thickness of 0.1-0.3 mm.

4. The sewing process according to claim 1, characterized in that: The molding equipment in step (4) is a segmented air pressure mold, and the pressure at the toe and heel area is 10%-15% higher than that at the middle area.

5. The sewing process according to claim 1, characterized in that: The waterproof coating in step (5) is a fluorine-containing resin material, and the spraying amount is 5-8g / double, which forms a micron-level hydrophobic film layer after curing.

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