A processing method for reducing deformation of a garment splice

Abstract

The application discloses a processing method for reducing deformation of a garment splicing part, and belongs to the technical field of garment processing. The method comprises the following steps: obtaining two garment patterns to be spliced and determining a splicing seam area; performing directional stress pre-relaxation treatment on the splicing seam area; measuring the size change of the seam area before and after the treatment, calculating the size change rate, and determining residual stress distribution data; dividing the splicing seam into at least two curvature sections according to the curvature change of the splicing seam and the residual stress distribution data, and determining the stress compensation coefficients of the sections; and performing sewing by matching corresponding stitch length and feed amount parameters for different curvature sections, and monitoring the thread tension in real time through a thread tension sensor and dynamically adjusting the feed amount during the sewing process. The processing method for reducing deformation of a garment splicing part is adopted, the deformation of the splicing part is systematically controlled by releasing stress from the source and adjusting in real time during sewing, and the flatness of the splicing part is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of garment processing technology, and in particular to a processing method for reducing deformation at garment seams. Background Technology

[0002] During the sewing process, seams are prone to deformation problems such as wrinkling, shrinkage, and dimensional changes, a phenomenon that has long plagued the garment manufacturing industry. The causes of deformation at seams are multifaceted.

[0003] First, during the cutting process, the cutting blade shears and compresses the fabric, leaving residual internal stress at the cut edges, i.e., the seam allowance area. If this residual stress is not treated before entering the sewing process, the fabric will spring back or shrink after sewing, resulting in dimensional changes and uneven appearance at the seams.

[0004] Secondly, the sewing process itself introduces new stress into the fabric. When the needle and thread penetrate the fabric at high speed, they introduce thread tension into the seam area, creating internal stress. Furthermore, the geometry of the seam significantly affects the fabric's stress state. Straight seams distribute stress relatively evenly, while curved seams, such as armhole seams and curved hems, tend to cause fabric accumulation or stretching at the apex or trough of the curve during sewing. If the stress differences in different curvature sections are not properly controlled, they will further exacerbate deformation at the seam.

[0005] To address the aforementioned problems, some solutions already exist in the prior art. For example, patent CN102936828B discloses a method for applying tension to the seam bob, which eliminates internal stress generated during sewing by applying 1%-10% tension to the seam bob or seam allowance and performing heat treatment under stress. Patent CN116695342B relates to a robot-assisted sewing feed trajectory planning method based on curvature segmentation, which plans the sewing speed by analyzing the curvature changes of the sewing curve. However, these prior technologies each have limitations: the former requires applying external tension to the seam allowance before sewing and using a dedicated tensioning device, making the process complex and reliant on external tooling; the latter mainly focuses on speed control during sewing and does not address the treatment of internal stress in the fabric before sewing. Furthermore, since the stress state of the fabric changes dynamically during the sewing process due to the combined effects of needle penetration and fabric feeding, deformation will still occur if stress is only eliminated before sewing without compensating for the stress differences during the sewing process. Conversely, if parameters are adjusted only based on curvature without taking the pre-sewing stress state into account, the pre-set process parameters will not match the actual state of the fabric, and the compensation effect will be greatly reduced.

[0006] Therefore, there is an urgent need for a processing method to reduce the deformation of garment seams, so as to simultaneously control residual stress before seaming and differential stress during seam. Summary of the Invention

[0007] The purpose of this invention is to provide a processing method that reduces deformation at the seams of clothing, thereby solving the above-mentioned problems.

[0008] This invention provides a processing method for reducing deformation at garment seams, comprising the following steps: S1. Obtain the two garment pieces to be spliced, and determine the seam allowance area where the two pieces meet. S2. Perform directional stress pre-relaxation treatment on the seam allowance area to release the internal stress remaining in the seam allowance area after the cut piece is cut, so that the seam allowance area enters a low stress state; the directional stress pre-relaxation treatment is only performed on the seam allowance area and does not perform full-area relaxation treatment on the main fabric of the cut piece. S3. Measure the dimensional change of the seam area before and after the S2 treatment, calculate the dimensional change rate, and determine the residual stress distribution data of the seam area based on the dimensional change rate. S4. Based on the curvature change of the splice joint and the residual stress distribution data, divide the splice joint into at least two curvature sections and determine the stress compensation coefficient of each curvature section. S5. For different curvature sections, the corresponding stitch length and feed amount parameters are matched according to their respective stress compensation coefficients. Without external shaping fixtures, the splicing and sewing are completed according to the stitch length and feed amount corresponding to each curvature section. During the sewing process, the thread tension is monitored in real time by the sewing machine's thread tension sensor. When the monitored thread tension exceeds the preset threshold, the feed amount parameter of the current curvature section is dynamically adjusted. S6. Sewing is complete, resulting in the pieced-together garment.

[0009] Preferably, in step S3, several pairs of reference markers are set along the seam length in the seam allowance area, with an initial spacing of L0 between each pair of reference markers; the spacing L1 between each pair of reference markers after processing in step S2 is measured; the dimensional change rate δ at each location is calculated using the following formula: ; The sign of the dimensional change rate δ reflects the direction of the residual stress, and the absolute value of δ reflects the relative level of the residual stress.

[0010] Preferably, in S3, the residual stress distribution data is the residual strain sequence R(x) = {ε_t} of each marked point pair along the joint length direction. r,1 ,ε r,2 ,...,ε r,n}, where n is the total number of marked point pairs, and ε is the residual strain at each location. r,i Calculate using the following formula: ; Where L 0,i L is the initial spacing between the i-th pair of markers. 1,i ε is the spacing between the i-th pair of markers after processing in S2; r,i The larger the absolute value, the higher the residual internal stress at that location before pre-relaxation.

[0011] Preferably, in S4, the stress compensation coefficient is determined according to the following formula: ; Where K c Let |ε be the stress compensation coefficient. r | represents the absolute value of the residual strain at that location, ε ref For reference residual strain, α is the fabric type coefficient; K c The larger the value, the higher the stress compensation intensity required at that location.

[0012] Preferably, the reference residual strain ε ref Take the median or average value of the absolute values ​​of residual strain in all marked point pairs; the fabric type coefficient α is obtained through pre-calibration, and the value of α for woven fabrics ranges from 0.8 to 1.2, while the value of α for elastic knitted fabrics ranges from 1.5 to 2.5.

[0013] Preferably, in S5, the stitch pitch P and feed rate F of each curvature section are adjusted according to the following formula: ; ; Where P0 is the reference stitch length for this curvature section, F0 is the reference feed rate for this curvature section, β is the stitch length adjustment coefficient, and γ is the feed rate adjustment coefficient; K c The larger the size, the smaller the stitch spacing and the smaller the fabric feed.

[0014] Preferably, the values ​​of the needle spacing adjustment coefficient β and the fabric feed adjustment coefficient γ are both in the range of 0.1 to 0.3, and β > γ.

[0015] Preferably, in S4, the curvature segment division method includes: dividing the straight segment in the splice seam into the first curvature segment, dividing the inwardly concave arc splice segment into the second curvature segment, and dividing the outwardly convex arc splice segment into the third curvature segment.

[0016] Preferably, during the sewing process of S5, the feed tension of the upper and lower layers of fabric is maintained within the range of 0 to 5% micro-elongation.

[0017] Preferably, in S2, the directional stress pre-relaxation treatment is low-temperature steam ironing relaxation, the ironing temperature is 60°C to 95°C, the steam action time on the seam area is 3 seconds to 12 seconds, and no tensile force is applied to the seam area during the ironing process.

[0018] Therefore, the above-described processing method for reducing deformation at garment seams has the following beneficial effects: (1) Before sewing, the seam allowance area is subjected to directional stress pre-relaxation treatment to bring the seam allowance area into a low-stress steady state. This treatment is only applied to the seam allowance area, which ensures the full release of residual cutting stress and avoids excessive impact on the overall size of the cut piece. After the seam allowance enters a low-stress steady state, there will be no uncontrollable deformation caused by the random release of residual cutting stress during subsequent sewing, providing a stable processing benchmark for the entire splicing process.

[0019] (2) By setting reference points in the seam allowance area and measuring the dimensional changes before and after the pre-relaxation treatment, the originally invisible residual stress is transformed into quantifiable dimensional change rate data. Operators only need to use chalk and a soft measuring tape to complete the measurement, without the need for any electronic equipment, and can know the distribution of residual stress along the seam allowance length. This quantitative characterization method ensures that the determination of sewing parameters does not rely solely on subjective experience, thus guaranteeing the accuracy and repeatability of process decisions.

[0020] (3) Simultaneously, based on the geometric curvature and residual stress distribution data of the seam, joint segmentation is performed and the stress compensation coefficient of each curvature segment is determined. This method ensures that the sewing parameters of each segment fully consider the differences in fabric stress caused by curvature changes, as well as the actual residual stress level of that segment, achieving differentiated and precise compensation. Different stitch lengths and feed amounts are matched to different curvature segments, so that the stress state of the fabric tends to be balanced throughout the entire seam length during the sewing process.

[0021] (4) Based on the differentiated sewing parameter settings, the sewing machine's built-in thread tension sensor is used to monitor the thread tension in real time during the sewing process. When the tension exceeds the preset threshold, the feed rate parameter is dynamically adjusted. Pre-sewing relaxation provides feedforward stress pre-release, and real-time feedback during sewing provides dynamic adjustment. The two form a complementary dual guarantee mechanism to ensure that the stress state of the fabric is always within the control range throughout the sewing process.

[0022] (5) The entire process is completed without external tooling, without relying on auxiliary tools such as lining strips or pressing molds. The entire process can be completed using only the sewing machine's own fabric feeding mechanism and parameter adjustment function. No additional tooling investment is required, and it can be directly promoted and applied on existing garment production lines, with good industrial applicability and cost advantages.

[0023] (6) Further stress equalization post-treatment is carried out on the splicing seam area after sewing. This step, together with the pre-relaxation treatment before sewing, forms a complete stress management system. The residual stress from cutting is released before sewing, and differential parameter control and real-time feedback adjustment are implemented during sewing. The differential stress introduced by sewing is balanced after sewing. The stress in the entire process of garment splicing is effectively controlled.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of a processing method for reducing deformation of garment seams according to the present invention. Detailed Implementation

[0026] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0028] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0029] This invention provides a processing method for reducing deformation at garment seams, comprising the following steps: S1. Obtain the two garment pieces to be joined and determine the seam allowance area where they meet. After the garment pieces are cut, it is necessary to determine which edges are joined together; this joining area is the seam allowance area. The operator marks the seam allowance position on the garment pieces according to the garment pattern requirements, determining the applicable range for subsequent stress treatment. This step can be completed in conventional garment production without special equipment.

[0030] S2. Perform directional stress pre-relaxation treatment on the seam allowance area to release the internal stress remaining in the seam allowance area after the fabric piece is cut, bringing the seam allowance area into a low-stress state. This directional stress pre-relaxation treatment is only applied to the seam allowance area and does not perform a full-area relaxation treatment on the main fabric piece. During the cutting process, the cutting blade shears and compresses the fabric, leaving residual internal stress in the seam allowance area. Directly sewing with this residual stress will cause the fabric to spring back or shrink after sewing, resulting in wrinkles or deformation at the seam. This step uses low-temperature steam ironing to locally treat the seam allowance area, causing the fiber molecular chains to rearrange under the influence of heat and moisture, releasing the internal stress remaining from the cutting process. The key point is "directional"—treating only the seam allowance area and not the main fabric piece ensures stress release while avoiding excessive impact on the overall fabric dimensions. In actual operation, the operator should use a steam iron to iron the seam allowance area for 3-12 seconds, taking care not to pull the fabric during ironing.

[0031] S3. Measure the dimensional changes of the seam allowance area before and after treatment S2, calculate the dimensional change rate, and determine the residual stress distribution data of the seam allowance area based on the dimensional change rate. Residual stress in the fabric cannot be directly observed with the naked eye, but it will manifest as dimensional changes after stress release. Locations with high stress will show more pronounced rebound or shrinkage after release. This step involves setting several pairs of reference markers in the seam allowance area, such as marking a pair with chalk every 2-3 cm, with a fixed spacing of 5 cm between each pair. The spacing between each pair of markers is measured before and after treatment S2, and the dimensional change rate at each location is calculated. A larger dimensional change rate indicates higher residual internal stress at that location before pre-relaxation. Arranging the dimensional change rates of each pair of markers along the seam allowance length yields the distribution of residual stress along the seam allowance.

[0032] S4. Based on the curvature variation of the seam and the residual stress distribution data, divide the seam into at least two curvature segments and determine the stress compensation coefficient for each curvature segment. Seams with different curvatures experience different stress states during sewing; straight segments experience uniform stress, convex arc segments tend to have fabric accumulation, and concave arc segments are easily stretched. This step combines the residual stress data measured in S3 with the geometric curvature of the seam to divide the seam allowance into zones: areas with high residual stress require stronger sewing compensation (smaller stitch length, smaller fabric feed), while areas with low residual stress can use conventional parameters. The stress compensation coefficient is a quantitative indicator that converts "high or low residual stress" into "the range of sewing parameter adjustments." The greater the residual strain, the larger the compensation coefficient, and the smaller the corresponding stitch length and fabric feed.

[0033] S5. For different curvature sections, the corresponding stitch length and feed amount parameters are matched according to their respective stress compensation coefficients. Without external shaping fixtures, the splicing and sewing are completed according to the stitch length and feed amount corresponding to each curvature section. During the sewing process, the thread tension is monitored in real time by the sewing machine's thread tension sensor. When the monitored thread tension exceeds the preset threshold, the feed amount parameter of the current curvature section is dynamically adjusted. This is the core execution step of the invention, which involves two levels of control: Feedforward control: Based on the stress compensation coefficients for each curvature segment determined by S4, the stitch length and feed rate for each segment are preset. The stitch length affects the density of the stitches and the strength of the seam, while the feed rate affects the speed at which the fabric is pushed and the degree of fabric stretching. Segments with high residual stress use a smaller stitch length (closer stitching) and a smaller feed rate (reduced fabric advance) to enhance stress compensation at that location.

[0034] Feedback control: During the sewing process, the sewing machine's built-in thread tension sensor monitors the thread tension in real time. There is a mechanical relationship between thread tension and fabric tension; when the fabric is overstretched, the thread needs to withstand greater tension to sew two layers of fabric together. When the thread tension exceeds a preset threshold, the control system automatically reduces the fabric feed, allowing the fabric tension to return to a normal range. This closed-loop control achieves real-time stress adjustment during the sewing process.

[0035] S6. Sewing is complete, resulting in the pieced-together garment.

[0036] After completing the above steps, the two pieces of fabric undergo stress release and quantitative assessment before seaming, as well as differential parameter control and real-time feedback adjustment during seaming. As a result, the deformation of the fabric pieces at the seam of the finished garment is significantly reduced.

[0037] In S3, several pairs of reference markers are set along the seam allowance length in the seam allowance area, with an initial spacing of L0 between each pair of reference markers; the spacing L1 of each pair of reference markers after processing in S2 is measured; the dimensional change rate δ at each location is calculated using the following formula: ; The sign of the dimensional change rate δ reflects the direction of the residual stress, and the absolute value of δ reflects the relative level of the residual stress.

[0038] Specifically, after determining the seam allowance area in S1, use chalk or a water-soluble pen to make a pair of marks every 2-3 cm along the length of the seam allowance, with a fixed spacing of L0 (e.g., 50 mm) between each pair of marks. Record the initial spacing of each pair of marks using a soft measuring tape or ruler. After steam ironing in S2, measure the new spacing L1 of each pair of marks at the same location. Substitute these values ​​into the formula to calculate the rate of dimensional change. A positive δ value indicates that the fabric has stretched after relaxation, indicating the presence of tensile stress; a negative δ value indicates that the fabric has shortened after relaxation, indicating the presence of compressive stress. The larger the absolute value of δ, the higher the original residual stress at that location. Arranging the δ values ​​of each pair of marks according to the seam allowance length creates a stress distribution map.

[0039] In S3, the residual stress distribution data is the residual strain sequence R(x) = {ε_t} of each marked point along the joint length direction. r,1 ,ε r,2 ,...,ε r,n}, where n is the total number of marked point pairs, and ε is the residual strain at each location. r,i Calculate using the following formula: ; Where L 0,i L is the initial spacing between the i-th pair of markers. 1,i ε is the spacing between the i-th pair of markers after processing in S2; r,i The larger the absolute value, the higher the residual internal stress at that location before pre-relaxation.

[0040] Specifically, the calculated rate of dimensional change δ for each pair of marked points is defined as the residual strain ε at that location. r Residual strain is essentially the proportion of strain released during pre-relaxation to the original size. The ε of all marked point pairs... r Arranging these numbers along the seam allowance length creates a data set representing the residual stress distribution. This data set doesn't require complex instruments; it can be obtained simply by measuring with a tape measure. However, it accurately reflects the trend of residual stress along the seam allowance. Locations with higher values ​​require more compensation during sewing.

[0041] In S4, the stress compensation coefficient is determined according to the following formula: ; Where K c Let |ε be the stress compensation coefficient. r | represents the absolute value of the residual strain at that location, ε ref For reference residual strain, α is the fabric type coefficient; K c The larger the value, the higher the stress compensation intensity required at that location.

[0042] Specifically, the stress compensation coefficient K cIt is an intermediate variable that transforms the "residual strain measurement value" into the "sewing parameter adjustment amount". In the formula, |ε r | represents the absolute value of the residual strain at that location, ε ref α is the median or average of the absolute values ​​of residual strain across all marked point pairs (serving as a reference for normal levels). The ratio of the two reflects the level of residual stress at that location relative to normal levels. α is a fabric type coefficient; because different fabrics have different stress-strain relationships, elastic fabrics exhibit higher stress at the same strain, resulting in a higher α value. K c The larger the value, the more compensation is needed at that location (smaller stitch length, smaller feed rate). The formula uses α and ε... ref It can be pre-calibrated through a small number of process experiments, and then put into production.

[0043] Reference residual strain ε ref Take the median or average value of the absolute values ​​of residual strain in all marked point pairs; the fabric type coefficient α is obtained through pre-calibration, and the value of α for woven fabrics ranges from 0.8 to 1.2, while the value of α for elastic knitted fabrics ranges from 1.5 to 2.5.

[0044] Specifically, ε ref Either the median or the average value can be chosen; the aim is to establish a reference standard at a normal level, where the residual strain equals ε. ref Location, K c =α, with moderate compensation; residual strain is higher than ε. ref Location, K c >α, employing stronger compensation. The value of α is predetermined through a small number of process experiments: samples of the same fabric are taken, residual strain is measured under the same pre-relaxation conditions, and then the α value corresponding to the best compensation effect is determined through trial sewing. Woven fabrics have a tight structure and low elasticity, resulting in a steeper stress-strain relationship, and therefore a relatively smaller α value (0.8-1.2); elastic knitted fabrics have a loose structure and high elasticity, resulting in higher stress corresponding to the same strain, and therefore a relatively larger α value (1.5-2.5).

[0045] In S5, the stitch length P and feed rate F for each curvature section are adjusted according to the following formula: ; ; Where P0 is the reference stitch length for this curvature section, F0 is the reference feed rate for this curvature section, β is the stitch length adjustment coefficient, and γ is the feed rate adjustment coefficient; K c The larger the size, the smaller the stitch spacing and the smaller the fabric feed.

[0046] Specifically, P0 is the reference stitch length for this curvature section, i.e., the standard stitch length without considering stress compensation, and F0 is the reference feed rate. β and γ are adjustment coefficients that control the stitch length and feed rate as K changes. c Sensitivity to change. The logic of the formula is: K c The larger the value (the higher the residual stress), the greater the reduction in stitch length and feed rate from the baseline value. A smaller stitch length means denser stitches and higher seam strength; a smaller feed rate means the fabric is pushed at a slower speed and the fabric is stretched less.

[0047] The values ​​of the needle spacing adjustment coefficient β and the fabric feed adjustment coefficient γ are both in the range of 0.1 to 0.3, and β > γ.

[0048] Specifically, β controls the needle pitch as K c The sensitivity to changes in feed rate (γ) is controlled by the sensitivity of the feed rate to changes in K_c. Both are pre-calibrated through process experiments. β>γ means that the stitch length is more sensitive to residual stress than the feed rate; under the same residual stress, the adjustment range of the stitch length is greater than that of the feed rate. This is because the stitch length directly affects the physical strength of the seam and is the most direct means of controlling deformation; while the feed rate affects the dynamic stress on the fabric during sewing more and is an auxiliary adjustment method. A value range of 0.1-0.3 ensures a moderate adjustment range; too small a value results in insufficient compensation, while too large a value may lead to overcompensation and new deformation.

[0049] In S4, the curvature segment division method includes: dividing the straight segment in the splice seam into the first curvature segment, dividing the inwardly concave arc splice segment into the second curvature segment, and dividing the outwardly convex arc splice segment into the third curvature segment.

[0050] Specifically, the geometry of the seam determines the stress characteristics during sewing: Straight segments: distribute stress evenly, have the lowest sewing difficulty, and can be sewn using standard parameters; Outward convex arc (seam bulges outward): When sewing, the fabric tends to pile up and wrinkle at the apex of the arc, requiring a smaller stitch length and a smaller feed rate to "digest" the excess fabric. Concave arc section (seam recessed inward): When sewing, the fabric is easily stretched at the bottom of the arc, and appropriate parameter adjustments are needed to avoid stretching and deformation.

[0051] In practice, operators can visually determine the type of each segment based on the seam curves on the garment pattern and then divide it into segments without the need for complex calculations.

[0052] During the sewing process of S5, the feed tension of the upper and lower layers of fabric is maintained within the range of 0 to 5% micro-elongation.

[0053] Specifically, during sewing, the top and bottom layers of fabric pieces move forward under the push of the feed dogs. If the feed rate is too high or the operator pulls the fabric, the fabric pieces will be stretched (extension exceeding 5%). After sewing, the fabric will spring back, causing shrinkage and wrinkling at the seam. This step requires that the elongation of the fabric pieces be controlled within a slight range of 0-5% throughout the entire sewing process, neither too loose nor too stretched. In practice, the operator controls the feed force by feel, while simultaneously adjusting the automatic feed rate to ensure that the fabric pieces remain in a low-stress state, close to their natural state, throughout the entire sewing process.

[0054] In S2, the directional stress pre-relaxation treatment is low-temperature steam ironing relaxation, with an ironing temperature of 60°C to 95°C, and the steam action time on the seam area is 3 to 12 seconds, and no tensile force is applied to the seam area during the ironing process.

[0055] Specifically, low-temperature steam ironing at 60-95℃ provides sufficient heat and moisture to increase the mobility of fiber molecular chains and release internal stress without causing heat damage or excessive shrinkage of the fabric. A 3-12 second application time is sufficient for the steam to penetrate the fibers in the seam area, completing the stress release. No stretching force should be applied during ironing; pulling the fabric while ironing negates the stress-relaxation effect, rendering the pre-relaxation treatment meaningless. The operator simply needs to gently place the iron on the seam area and apply natural pressure.

[0056] To more clearly and in detail introduce the processing method for reducing deformation of garment splicing parts provided by the embodiments of the present invention, the following description will be based on specific embodiments.

[0057] Example 1 Taking the side seam splicing of woven cotton fabric garments as an example, the processing method to reduce the deformation of the spliced ​​parts of the garment is as follows: S1. Obtain the two garment pieces to be spliced ​​and determine the seam allowance area where the two pieces meet.

[0058] Take two pre-cut woven cotton fabric garment pieces, designated as the front and back pieces. Based on the garment pattern requirements, determine the position of the side seam where the front and back pieces meet. Mark the seam allowance area at this position, with a seam allowance width of 1cm. On the seam allowance area, use chalk to draw an auxiliary line along the seam allowance length, 0.5cm from the edge of the fabric piece. This will serve as a reference line for subsequent marking and sewing.

[0059] S2. Perform directional stress pre-relaxation treatment on the seam allowance area to release the internal stress remaining in the seam allowance area after the fabric piece is cut, so that the seam allowance area enters a low stress state; the directional stress pre-relaxation treatment is only performed on the seam allowance area and does not perform full-area relaxation treatment on the main fabric of the fabric piece.

[0060] Set the steam iron to 80℃ and the steam output to a moderate level. Lay the seam allowance of the two fabric pieces flat on the ironing board and use the iron to gently steam the seam allowance to relax it. When ironing, the iron should only cover the seam allowance, approximately 1.5cm wide, and cover the seam allowance and 0.25cm on each side; do not iron the main fabric. The ironing time is 8 seconds. During ironing, the operator should only rely on the iron's own weight to apply pressure naturally, without applying any additional stretching force to the seam allowance. After ironing, lay the fabric pieces flat to cool for 30 seconds, allowing the seam allowance to naturally set and enter a low-stress state.

[0061] S3. Measure the dimensional changes of the seam area before and after the S2 treatment, calculate the dimensional change rate, and determine the residual stress distribution data of the seam area based on the dimensional change rate.

[0062] After determining the seam allowance area in S1 and before processing in S2, 10 pairs of reference marks are set along the seam allowance length. The spacing between adjacent marks is 2cm, and the initial distance L0 between the two marks in each pair is 50mm. The initial distance L0 between each pair of marks is measured and recorded using a soft measuring tape. 0，i (i=1,2,…,10).

[0063] After completing the S2 low-temperature steam ironing relaxation process, wait for the cut pieces to cool to room temperature, and then use the same soft measuring tape to measure the new spacing L of each pair of marked points at the same location. 1，i (i=1,2,…,10).

[0064] Calculate the rate of change of size δ of each marker point relative to its position using the following formula. i : ; The dimensional change rates measured for the 10 marked point pairs were: +0.6%, +0.8%, +1.2%, +1.5%, +1.8%, +1.6%, +1.3%, +0.9%, +0.7%, and +0.5%. All dimensional change rates were positive, indicating that the seam allowance of the woven cotton fabric retained tensile stress after cutting, and rebounded after pre-relaxation treatment.

[0065] The rate of change of size δ for each pair of marked points i The residual strain ε at this location r,iArranged along the seam allowance length, the residual stress distribution data R(x) = {0.6%, 0.8%, 1.2%, 1.5%, 1.8%, 1.6%, 1.3%, 0.9%, 0.7%, 0.5%} was obtained. This data sequence shows that the residual strain is higher in the middle area of ​​the seam allowance (the position of the 4th to 6th marked points, corresponding to the waist curve area of ​​the side seam), and lower in the two end areas (corresponding to the straight waist and hip areas of the side seam).

[0066] S4. Based on the curvature change and residual stress distribution data of the splice joint, divide the splice joint into at least two curvature sections and determine the stress compensation coefficient of each curvature section.

[0067] Observe the geometry of the side seam in this embodiment: the upper part of the side seam (from the waist to the armpit) is a slightly outward convex arc, which is an outward convex arc; the middle part of the side seam (near the waist) is a slightly inward concave arc, which is an inward concave arc; the lower part of the side seam (from the hip to the hem) is basically a straight line.

[0068] Based on the curvature geometry, the splice seam is initially divided into three curvature sections: the first curvature section is the straight section at the bottom of the side seam, the second curvature section is the concave arc section in the middle of the side seam, and the third curvature section is the convex arc section at the top of the side seam. Combined with the residual stress distribution data measured in S3, the residual strain is highest at the 4th to 6th marker pairs corresponding to the concave arc section in the middle of the side seam, ranging from 1.5% to 1.8%; the residual strain is moderate at the 7th to 8th marker pairs corresponding to the convex arc section in the top of the side seam, ranging from 0.9% to 1.3%; and the residual strain is relatively low at the 1st to 3rd marker pairs and the 9th to 10th marker pairs corresponding to the straight section at the bottom of the side seam, ranging from 0.5% to 0.8%. Therefore, the above three-segment division is confirmed to be reasonable.

[0069] Take the median value ε of the absolute value of the residual strain at all marked points. ref =0.95%. The fabric type coefficient α of this woven cotton fabric was pre-calibrated to 1.0 through process experiments.

[0070] Calculate the stress compensation coefficient K for each curvature section using the following formula. c : ; First curvature segment (straight line segment): Take the marked points within this segment and pair them with ε. r The average value is 0.65%, K c =1.0×0.65% / 0.95%≈0.68.

[0071] Second curvature segment (concave arc segment): Take the marked points within this segment relative to ε r The average value is 1.63%, K c =1.0×1.63% / 0.95%≈1.72.

[0072] Third curvature segment (convex arc segment): Take the marked points within this segment relative to ε r The average value is 1.10%, K c =1.0×1.10% / 0.95%≈1.16.

[0073] S5. For different curvature sections, match the corresponding stitch length and feed amount parameters according to their respective stress compensation coefficients. Without external shaping fixtures, complete the splicing and sewing according to the stitch length and feed amount corresponding to each curvature section. During the sewing process, the sewing machine's thread tension sensor monitors the thread tension in real time. When the monitored thread tension exceeds the preset threshold, the feed amount parameter of the current curvature section is dynamically adjusted.

[0074] This embodiment uses an industrial flatbed sewing machine (BrotherBAS-342K series) equipped with a surface tension sensor for sewing.

[0075] The reference stitch length P0 and reference feed amount F0 for each curvature section are preset according to the fabric type and process requirements: straight section P0=2.6mm, F0=2.6mm / needle; concave arc section P0=2.8mm, F0=2.8mm / needle; convex arc section P0=2.4mm, F0=2.4mm / needle.

[0076] The needle spacing adjustment coefficient β is pre-calibrated to 0.20, and the fabric feed adjustment coefficient γ is pre-calibrated to 0.15 (β>γ).

[0077] Calculate the adjusted stitch length P and feed rate F for each curvature section using the following formulas: ; ; First curvature segment (straight line segment, K) c =0.68): P=2.6×(1-0.20×0.68)=2.6×0.864=2.25mm; F = 2.6 × (1 - 0.15 × 0.68) = 2.6 × 0.898 = 2.33 mm / needle; The second curvature segment (concave arc segment, K) c =1.72): P=2.8×(1-0.20×1.72)=2.8×0.656=1.84mm; F = 2.8 × (1 - 0.15 × 1.72) = 2.8 × 0.742 = 2.08 mm / needle; The third curvature segment (outwardly convex arc segment, K) c =1.16): P=2.4×(1-0.20×1.16)=2.4×0.768=1.84mm; F = 2.4 × (1 - 0.15 × 1.16) = 2.4 × 0.826 = 1.98 mm / needle; During the sewing process, stitching is performed according to the stitch length and feed rate parameters corresponding to each section. The sewing machine's top thread tension sensor collects top thread tension data in real time, with a preset tension threshold of 3.5N. When the top thread tension sensor detects that the top thread tension exceeds 3.5N, the control system automatically reduces the feed rate in increments of 0.05mm / stitch until the top thread tension falls below 3.5N. When the top thread tension is below 2.0N, the control system automatically increases the feed rate in increments of 0.05mm / stitch until the top thread tension rises above 2.0N. Throughout the sewing process, the feed tension of the upper and lower fabric pieces is maintained within a micro-elongation range of 0% to 5%, without applying excessive stretching. The entire sewing process does not rely on any external shaping fixtures such as interfacing, pressing molds, or shaping jigs.

[0078] S6. Sewing is complete, resulting in the pieced-together garment.

[0079] After completing the above sewing, the two pieces of fabric are joined together at the side seam to obtain the side-seam-jointed garment piece. Upon visual inspection, the joined area is smooth and wrinkle-free, the seam is straight, and the deformation of the joined area is effectively controlled.

[0080] Example 2 Taking the armhole seam splicing of elastic knitted fabric (95% cotton + 5% spandex) as an example, the processing method to reduce the deformation of the garment splicing area is as follows: S1. Obtain the two garment pieces to be spliced ​​and determine the seam allowance area where the two pieces meet.

[0081] Take the sleeve and body pieces cut from the elastic knitted fabric, determine the seam allowance area where the sleeve cap curve of the sleeve piece and the armhole curve of the body piece meet, and the seam allowance width is 0.8cm.

[0082] S2. Perform directional stress pre-relaxation treatment on the splicing seam area.

[0083] Set the steam iron to 70℃. Since elastic knit fabric is temperature-sensitive, use a lower temperature and apply low-temperature steam ironing to the armhole seam area to relax it. Iron only the seam area, approximately 1.2cm wide, and do not iron the main fabric. The steam should be applied for 6 seconds. Do not apply any stretching force to the seam area during ironing.

[0084] S3. Measure the dimensional changes of the seam area before and after the S2 treatment, calculate the dimensional change rate, and determine the residual stress distribution data of the seam area based on the dimensional change rate.

[0085] Before S2 treatment, eight pairs of reference markers were set along the seam allowance of the armhole curve, with an initial spacing L0 of 40mm between each pair of markers. The initial spacing L0 of each pair of markers was measured and recorded. 0,i After completing the S2 processing, measure the new spacing L between each pair of marker points. 0,i .

[0086] According to the formula ; Calculate the dimensional change rate at each location. The dimensional change rates for the eight marked point pairs were measured to be: -0.3%, -0.5%, -0.8%, -1.2%, -1.0%, -0.6%, -0.4%, and -0.2%. All dimensional change rates were negative, indicating that the seam area of ​​the elastic knitted fabric retained compressive stress after cutting, which was released through shrinkage after pre-relaxation treatment. The δ... i As residual strain ε r,i The residual stress distribution data R(x) = {-0.3%, -0.5%, -0.8%, -1.2%, -1.0%, -0.6%, -0.4%, -0.2%} were obtained.

[0087] S4. Based on the curvature change and residual stress distribution data of the splice joint, divide the splice joint into at least two curvature sections and determine the stress compensation coefficient of each curvature section.

[0088] The armhole seam is generally curved, and based on the curvature variation, it can be divided into three segments: the upper segment has a smaller curvature, the middle segment has a larger curvature and bulges outward, and the lower segment has a smaller curvature. Residual stress distribution data shows that the middle segment, located at the 4th to 5th marked points, has the highest absolute residual strain value, ranging from 1.0% to 1.2%; the upper and lower segments have lower absolute residual strain values, ranging from 0.2% to 0.8%. Therefore, the armhole seam is divided into these three curvature segments.

[0089] Take the median value ε of the absolute value of the residual strain at all marked points. ref =0.55%. The fabric type coefficient α of this elastic knitted fabric was pre-calibrated to 2.0 through process experiments. Calculate the stress compensation coefficient for each curvature section.

[0090] S5. Match the corresponding stitch length and feed amount parameters for different curvature sections to complete the splicing and sewing without external shaping fixtures; during the sewing process, the feed amount is monitored and dynamically adjusted in real time by the surface tension sensor.

[0091] The sewing is performed using an industrial coverstitch machine equipped with a top thread tension sensor. According to the formula... and Calculate the adjusted stitch length and feed rate for each curvature section (β=0.25, γ=0.20). During sewing, the thread tension sensor monitors in real time, with a preset tension threshold of 2.8N. The feed rate is automatically adjusted when the tension exceeds this threshold. The feed tension of the upper and lower fabric pieces is maintained within a micro-elongation range of 0 to 5%. No external shaping fixtures such as interfacing or pressing molds are used throughout the entire process.

[0092] S6. Sewing is complete, resulting in the pieced-together garment.

[0093] The armhole seam is complete, the sleeve cap and armhole fit well, and the seam is smooth and wrinkle-free.

[0094] Example 3 Taking the curved hem seam of woven polyester-cotton blended fabric as an example, the processing method to reduce the deformation of the garment seam is as follows: it further includes a stress equalization post-treatment step after sewing is completed. Steps S1 to S6 of this embodiment are basically the same as those in Embodiment 1, except that the fabric is a woven polyester-cotton blend (65% polyester + 35% cotton), and the seam is an arc-shaped hem seam. In S2, the ironing temperature is 85℃, and the steam treatment time is 10 seconds. In S3, 12 pairs of reference markers are set, and after measuring the residual stress distribution data, the arc-shaped hem seam is divided into two curvature sections: an outwardly convex arc segment and an inwardly concave arc segment, based on the curvature. In S5, an industrial flat sewing machine equipped with a surface tension sensor is used to complete the sewing.

[0095] This embodiment further includes step S7 after S6: S7. After sewing is completed, stress equalization post-treatment is performed on the splice seam area: along the length direction of the splice seam, according to the curvature characteristics of each curvature section, differential ironing parameters that match the stitch length and fabric feed amount in step S5 are applied to the curvature section respectively.

[0096] After sewing, lay the assembled garment pieces flat on an ironing board. For the convex curves, the stitch length in S5 is 1.8mm and the feed rate is 1.9mm / stitch. Use a 75℃ steam iron to lightly iron for 3 seconds, moving the iron along the natural curve of the convex curve without applying additional pressure. For the concave curves, the stitch length in S5 is 2.2mm and the feed rate is 2.3mm / stitch. Use a 70℃ steam iron to lightly iron for 3 seconds, moving the iron along the natural curve of the concave curve. Differentiated ironing parameters matching the sewing parameters are used for each curvature section to balance the residual stress in each curvature section. The original dimensions of the garment pieces are not changed during finishing.

[0097] After finishing, the stress distribution of each section of the arc-shaped hem splice is more uniform, and the flatness of the splice area is further improved.

[0098] Comparative Example 1 The difference between this comparative example and Example 1 is that the directional stress pre-relaxation treatment step S2 is omitted, that is, the sewing is carried out directly after the cut pieces are cut.

[0099] The specific operation is as follows: Take the same woven cotton fabric garment piece as in Example 1, determine the side seam allowance area, and without any pre-relaxation treatment, directly divide the curvature into straight segments, concave arc segments, and convex arc segments based on the curvature change of the seam. Then, match the corresponding stitch length and fabric feed parameters for different curvature segments and sew them. During the sewing process, the surface tension sensor is also used for real-time monitoring and feedback adjustment.

[0100] After sewing, the seams were inspected, and obvious wrinkling was found at the side seams, especially in the concave and convex sections. The fabric shrinkage was uneven, and the smoothness of the seams was significantly lower than in Example 1. The fabric elongation at the seams was measured, and it was found that the elongation in some areas exceeded 8%, which is much higher than the 0-5% range in Example 1.

[0101] The results show that omitting the directional stress pre-relaxation treatment in S2 prevents the release of internal stress remaining in the seam allowance area during the fabric cutting process. Direct sewing leads to the concentrated release of stress during the sewing process, causing deformation at the joint. Even with subsequent curvature segmented differential sewing and real-time feedback adjustment, the deformation problem cannot be effectively solved because the pre-sewing stress was not released.

[0102] Comparative Example 2 The difference between this comparative example and Example 1 is that the residual stress distribution data measurement in S3 and the stress compensation coefficient calculation steps based on the residual stress data in S4 are omitted. The seam is segmented only according to the geometric curvature of the seam, and the stitch length and feed amount parameters of each curvature segment are determined only according to the curvature type, without considering the residual stress distribution data.

[0103] The specific operation is as follows: Take the same woven cotton fabric garment piece as in Example 1, and after performing the directional stress pre-relaxation treatment (S2), directly divide the seam into three curvature sections: a straight section, an inwardly concave arc section, and an outwardly convex arc section, based on the geometric shape of the seam. The stitch length and feed rate parameters for each curvature section are set only according to the curvature type. The outwardly convex arc section uniformly uses a small stitch length and a small feed rate, while the inwardly concave arc section uniformly uses a large stitch length and a large feed rate, without adjustment based on the residual stress distribution data (S3). During the sewing process, the surface tension sensor is used for real-time monitoring and feedback adjustment.

[0104] After sewing, observation of the seam revealed that although the overall flatness was better than that of Comparative Example 1 due to the S2 pre-relaxation treatment, slight wrinkling still occurred in the concave arc section in the middle of the side seam, where residual stress was high. This was because the stitch length and fabric feed were not adequately adjusted to compensate for the high residual stress in this area. Consequently, the flatness was not as good as in Example 1. Measurement of the residual strain in this area showed that although the S2 pre-relaxation treatment released some internal stress, stress concentration was re-generated during the sewing process because the sewing parameters were not differentiated to compensate for the residual stress distribution.

[0105] The results show that relying solely on curvature segmentation without considering residual stress distribution data cannot achieve accurate differentiated stress compensation, and areas with high residual stress still have the risk of deformation.

[0106] Comparative Example 3 The difference between this comparative example and Example 1 is that the order of the directional stress pre-relaxation treatment in S2 and the curvature segmentation differential sewing in S3-S5 is reversed. That is, curvature segmentation and differential sewing are performed first, and the pre-relaxation treatment is performed on the splice seam area after the sewing is completed.

[0107] The specific operation is as follows: Take the same woven cotton fabric garment piece as in Example 1, determine the side seam allowance area, and without any pre-relaxation treatment, directly divide the curvature according to the curvature change of the seam and match the corresponding stitch length and fabric feed parameters to complete the sewing. After sewing, perform low-temperature steam ironing relaxation treatment on the seam area, with an ironing temperature of 80℃ and an action time of 8 seconds.

[0108] After sewing, the seam was observed. Although ironing and loosening after sewing alleviated some of the internal stress generated during the sewing process, significant wrinkling and deformation had already occurred at the seam. Ironing after sewing could not eliminate the existing deformation. The flatness of the seam was measured and found to be significantly worse than in Example 1.

[0109] The results show that pre-relaxation treatment must be performed before sewing to release the residual internal stress from the cutting of the fabric pieces and provide a low-stress foundation for subsequent differentiated curvature segmentation sewing. Pre-relaxation treatment performed after sewing can only alleviate sewing stress but cannot eliminate the deformation that has already occurred.

[0110] Comparative Example 4 The difference between this comparative example and Example 1 is that external shaping tools such as lining strips and pressing molds are used to assist in the sewing process, rather than the process is completed without external shaping tools.

[0111] The specific operation is as follows: Take the same woven cotton fabric garment piece as in Example 1, attach a hot melt lining strip (0.8cm wide) to the side seam splicing area, and use an arc-shaped pressure mold to fix the shape of the splicing seam during the sewing process. Under this condition, perform curvature segmented differential sewing.

[0112] After sewing, the splicing area was observed to be flat and smooth. However, the following problems exist: (1) The pasting of the lining strip increases the process steps and material costs; (2) The arc-shaped pressing mold needs to be specially made for different curvatures, which increases the tooling cost and production preparation time; (3) The presence of the lining strip changes the feel of the fabric and affects the wearing comfort of the garment; (4) This solution relies on special tooling and is difficult to quickly adapt to splicing seams of different styles and curvatures.

[0113] In contrast, Example 1 achieves the same flatness effect without external shaping tooling, and the process is simpler, the cost is lower, and the applicability is wider.

[0114] The products obtained in Examples 1-3 and Comparative Examples 1-4 were tested as follows: Experiment 1: Evaluation of wrinkling level at splicing joints, with AATCC 88B as the testing standard; Test Method: After sewing, the samples were conditioned for 24 hours under standard atmospheric conditions (temperature 20±2℃, relative humidity 65±4%). Ten garment quality inspectors, referring to the AATCC 88B standard sample, used a 1-5 rating system, where level 1 indicates severe wrinkling and level 5 indicates no obvious wrinkling. The degree of wrinkling at the seams was independently rated, and the mode or average of the ratings was taken as the final grade. The test results are shown in Table 1 below. Table 1. Wrinkling Test Results

[0115] Example 1 improved by 2.5 levels compared to Comparative Example 1, demonstrating the decisive role of the S2 pre-relaxation treatment in wrinkle control. Example 1 improved by 1.5 levels compared to Comparative Example 2, indicating that the S3 stress characterization and S4 compensation coefficient calculation significantly contributed to further improving smoothness. Example 3 further improved upon Example 1, demonstrating the synergistic effect of the S7 post-seam stress equalization treatment.

[0116] Experiment 2: Measurement of dimensional change rate at spliced ​​joints; Test method: On the sewn garment piece, measure the actual dimension L of the seam allowance area along the length of the seam. actual The theoretical size L of the pattern design design For comparison, calculate the rate of dimensional change using the following formula: Dimensional change rate = (L actual-L design ) / L design ×100%; Positive values ​​indicate elongation at the seam, while negative values ​​indicate shrinkage. Measurements were taken immediately after sewing to reflect immediate deformation and after one standard washing cycle (GB / T 8629, 5A program, water temperature 40℃, tumble drying) to reflect deformation after washing. The test results are shown in Table 2 below. Table 2. Dimensional Change Rate Test Results (Total Side Seam Length 500mm, Unit: mm)

[0117] In Example 1, the dimensional change rate after sewing was only about 1 / 5 of that in Comparative Example 1, demonstrating that the S2 pre-relaxation treatment effectively avoided uncontrollable deformation during sewing by releasing residual cutting stress in advance. The dimensional change rate after washing in Example 1 was still much lower than that in Comparative Example 1, proving the durability of the improvement effect of the present invention. In Example 3, the dimensional change rate after sewing was only +0.10%, and remained at +0.10% after washing, indicating that differentiated ironing after sewing further stabilized the dimensions of the spliced ​​parts.

[0118] Experiment 3: Real-time monitoring of fabric elongation during sewing process; Test method: During the sewing process, a pair of reference marks are set on the upper and lower layers of fabric, with a spacing of 50mm between the marks, located approximately 30mm in front of the presser foot of the sewing machine. The change in the spacing between the marks is continuously monitored during the sewing process using an industrial camera or high-precision vernier calipers. The real-time elongation rate is calculated using the following formula: Elongation = (L current -L initial ) / L initial ×100%; Data was recorded at 50mm sewing length intervals, and the maximum and average values ​​were taken over the entire sewing length. The test results are shown in Table 3 below; Table 3 Elongation Test Results

[0119] In Example 1, the maximum elongation was controlled within the 5% threshold, and did not exceed the limit throughout the entire seam length. In Comparative Example 1, the maximum elongation far exceeded the 5% threshold, and 35% of the sewing time was outside the limit, demonstrating that after the S2 pre-relaxation treatment brought the seam allowance into a low-stress steady state, even with real-time feedback adjustment, the fabric stretching during sewing could still be significantly reduced. Although the maximum elongation in Comparative Example 2 was lower than in Comparative Example 1, it still exceeded the limit for 18% of the sewing time. This shows that the S3 stress characterization and S4 compensation coefficient calculation provided more accurate initial parameter settings for real-time feedback, significantly reducing the pressure of feedback adjustment.

[0120] Experiment 4: Comprehensive evaluation of deformation at the joints after washing; Test method: The patchwork garment pieces prepared in each embodiment and comparative example were subjected to 5 standard washing cycles (5A program, water temperature 40℃, standard detergent, tumble dry) according to GB / T 8629 "Home Washing and Drying Procedures for Textile Testing". After each wash, the following three indicators were measured: (1) AATCC 88B wrinkle grade; (2) dimensional change rate of the patchwork area; (3) twist rate at the seam. The average value after 5 washes was taken as the final result. The test results are shown in Table 4 below; Table 4 Comprehensive Evaluation Test Results

[0121] After five standard washes, the wrinkling level of Example 1 was still significantly higher than that of Comparative Example 1, the dimensional change rate was only 1 / 5 of that of Comparative Example 1, and the seam distortion rate was less than 1 / 4 of that of Comparative Example 1. This demonstrates that the present invention can not only control the immediate deformation of the seam, but its improvement effect can also be maintained after multiple washes. All indicators of Example 3 were better than those of Example 1, demonstrating that the post-seam stress equalization treatment has an additional contribution to improving wash durability.

[0122] Therefore, this invention employs the aforementioned processing method for reducing deformation at garment seam areas. Before sewing, a directional stress pre-relaxation treatment is applied to the seam allowance area, bringing it into a low-stress steady state. Since this treatment is only applied to the seam allowance area and not to the entire main fabric, it ensures the full release of residual cutting stress while avoiding excessive influence on the overall dimensions of the fabric. Once the seam allowance enters a low-stress steady state, uncontrollable deformation due to random release of residual cutting stress will not occur during subsequent sewing, providing a stable processing benchmark for the entire seam process. Experimental data shows that after processing the woven cotton fabric side seam according to the method of Example 1, the wrinkle level at the seam area reaches level 4.5 of the AATCC 88B standard, and the seam area is smooth, straight, and without obvious wrinkles. Under the same test conditions, Comparative Example 1, which omits the S2 pre-relaxation treatment, only has a wrinkle level of 2.0, with obvious wrinkles appearing at the seam area. The comparison shows that the S2 pre-relaxation treatment improved the wrinkling level by 2.5 levels, directly improving the splicing area from "obvious wrinkling" to "smooth and wrinkle-free".

[0123] By setting reference points in the seam allowance area and measuring dimensional changes before and after pre-relaxation treatment, the previously invisible residual stress is transformed into quantifiable dimensional change rate data. Operators only need chalk and a soft measuring tape to complete the measurement, without the need for any electronic equipment, to obtain the distribution of residual stress along the seam allowance length. This quantitative characterization method upgrades the determination of sewing parameters from relying on subjective experience to being based on evidence, ensuring the accuracy and repeatability of process decisions. Fabric elongation monitoring data during the sewing process shows that the maximum elongation rate in Example 1 was 4.2%, and the average elongation rate was 2.8%, with no instances exceeding the 5% threshold. Comparative Example 2, which omitted stress characterization in S3 and compensation coefficient calculation in S4, saw its maximum elongation rate rise to 6.3%, and 18% of the sewing time exceeded the limit. Steps S3 and S4 provided precise initial parameter settings for real-time feedback control, reducing the maximum elongation rate by 2.1 percentage points and effectively controlling fabric stretching during the sewing process.

[0124] Simultaneously, based on the geometric curvature and residual stress distribution data of the seams, joint segmentation was performed, and the stress compensation coefficient for each curvature segment was determined. This method ensures that the sewing parameters for each segment not only consider the differences in fabric stress caused by curvature changes but also fully respond to the actual residual stress level of that segment, achieving differentiated and precise compensation. Dimensional change rate measurement data shows that the dimensional change rate after sewing in Example 1 was only +0.30%, and remained at +0.50% after 5 washes. In Comparative Example 1, the dimensional change rate after sewing reached +1.60%, and increased to +2.50% after washing, a difference of more than five times. Although Comparative Example 2 underwent S2 pre-relaxation treatment, due to the omission of S3 stress characterization and S4 compensation coefficient calculation, the dimensional change rate after sewing still reached +0.90%, and increased to +1.30% after washing, both significantly worse than Example 1, demonstrating the significant improvement in dimensional stability achieved by joint segmentation compared to single curvature segmentation.

[0125] Based on differentiated sewing parameter settings, the sewing machine's built-in "top thread tension sensor" is further utilized to monitor the top thread tension in real time during the sewing process. When the tension exceeds a preset threshold, the fabric feed parameters are dynamically adjusted. Pre-sewing relaxation provides feedforward stress pre-release, while real-time feedback during sewing provides dynamic adjustment. These two elements form a complementary dual-protection mechanism, ensuring that the fabric's stress state remains within a controlled range throughout the sewing process. This improvement also exhibits good wash durability. Comprehensive deformation evaluation data after washing shows that after 5 standard washes, Example 1 maintains a wrinkle level of 4.0, a dimensional change rate of +0.50%, and a seam twist rate of only 1.2%. Comparative Example 1 showed a wrinkling level reduced to 1.5 after washing, with a dimensional change rate of +2.50% and a seam distortion rate as high as 5.6%. Comparative Example 3, by reversing the order of the S2 pre-relaxation treatment and the S3-S5 curvature segmented differentiated sewing, showed a wrinkling level of only 2.0 after washing, with a dimensional change rate of +1.80% and a seam distortion rate of 4.5%, indicating that deformation had already occurred and could not be eliminated through subsequent treatment. The deformation in all comparative examples significantly worsened after multiple washes, while Example 1 maintained excellent levels of all indicators after 5 washes, demonstrating that the "feedforward + feedback" dual protection mechanism has a lasting control effect on the deformation of the spliced ​​parts.

[0126] The entire process is completed without external shaping fixtures, relying solely on the sewing machine's own fabric feeding mechanism and parameter adjustment functions, without the need for auxiliary tools such as interfacing strips or pressing molds. This characteristic allows the method to be directly applied to existing garment production lines without additional tooling investment. While Comparative Example 4 achieves a similar level of smoothness to Example 1 in all aspects of flatness indicators, it relies on external shaping fixtures such as hot-melt interfacing strips and curved pressing molds. To achieve the same smoothness effect (wrinkling level 4.5, dimensional change rate +0.20%), Comparative Example 4 requires additional interfacing strip application and pressing mold manufacturing costs, and the presence of the interfacing strip alters the fabric's feel. In contrast, Example 1 achieves the same excellent smoothness effect without any external shaping fixtures, with a simpler process, lower production costs, and no impact on the fabric's feel.

[0127] Further stress equalization post-treatment is performed on the seam area after sewing. Differentiated ironing parameters are applied along the seam length according to the curvature characteristics of each curvature segment, so that the residual differential stress in each curvature segment tends to be balanced after sewing. This step, together with the pre-relaxation treatment before sewing, forms a complete stress management closed loop. Experimental data shows that Example 3, which includes the S7 post-sewing stress equalization treatment, achieves a wrinkling level of 4.8, a dimensional change rate of only +0.10% after sewing, and maintains a dimensional change rate of +0.10% after 5 washes, with a seam twist rate of only 0.8%. Compared to Example 1, Example 3 further improves the wrinkling level by 0.3 levels, and significantly improves both the dimensional change rate and the seam twist rate, proving that the post-sewing differentiated ironing treatment can further stabilize the dimensional shape of the spliced ​​part on the basis of sewing and prolong the durability of the improvement effect.

[0128] Example 1, without external shaping fixtures, achieved a wrinkling level of 4.5, a dimensional change rate of only +0.30%, and maintained excellent performance across all indicators after washing, outperforming all comparative examples. Comparative Example 1, omitting S2, showed a 2.5-level decrease in wrinkling and a more than 5-fold increase in dimensional change rate, demonstrating that the S2 pre-relaxation treatment is a crucial step in controlling deformation at its source. Comparative Example 2, omitting S3 and S4, showed inferior performance across all indicators compared to Example 1, proving the indispensability of quantitative stress characterization and compensation coefficient calculation. Comparative Example 3, after changing the order of steps, showed significant deformation, demonstrating that S2 must be applied pre-processed to provide adequate protection. Example 3, building upon Example 1, further added S7 post-seam stress equalization treatment, achieving a wrinkling level of 4.8, a dimensional change rate of only +0.10%, and a seam twist rate of only 0.8%, with all indicators reaching optimal levels, proving that S7 post-seam equalization treatment can further improve flatness and dimensional stability on the basis of sewing.

[0129] In summary, this invention systematically solves the deformation problem of garment splicing areas from four levels: stress source control, precise process decision-making, closed-loop process adjustment, and post-processing equalization, through a complete set of technical steps including "pre-sewing relaxation, stress characterization, joint segmentation, differentiated sewing, real-time feedback, and post-sewing equalization".

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A processing method for reducing deformation at garment seams, characterized in that, Includes the following steps: S1. Obtain the two garment pieces to be spliced, and determine the seam allowance area where the two pieces meet. S2. Perform directional stress pre-relaxation treatment on the splicing seam area to release the internal stress remaining in the seam area after the cut pieces are cut, so that the seam area enters a low stress state. S3. Measure the dimensional change of the seam area before and after the S2 treatment, calculate the dimensional change rate, and determine the residual stress distribution data of the seam area based on the dimensional change rate. S4. Based on the curvature change of the splice joint and the residual stress distribution data, divide the splice joint into at least two curvature sections and determine the stress compensation coefficient of each curvature section. S5. For different curvature sections, the corresponding stitch length and feed amount parameters are matched according to their respective stress compensation coefficients. Without external shaping fixtures, the splicing and sewing are completed according to the stitch length and feed amount corresponding to each curvature section. During the sewing process, the thread tension is monitored in real time by the sewing machine's thread tension sensor. When the monitored thread tension exceeds the preset threshold, the feed amount parameter of the current curvature section is dynamically adjusted. S6. Sewing is complete, resulting in the pieced-together garment.

2. The processing method for reducing deformation of garment seams according to claim 1, characterized in that, In S3, several pairs of reference markers are set along the seam allowance length in the seam allowance area, with an initial spacing of L0 between each pair of reference markers; the spacing L1 of each pair of reference markers after processing in S2 is measured; the dimensional change rate δ at each location is calculated using the following formula: ； The sign of the dimensional change rate δ reflects the direction of the residual stress, and the absolute value of δ reflects the relative level of the residual stress.

3. The processing method for reducing deformation of garment seams according to claim 1, characterized in that, In S3, the residual stress distribution data is the residual strain sequence R(x) = {ε_t} of each marked point along the joint length direction. r,1 ,ε r,2 ,...,ε r,n }, where n is the total number of marked point pairs, and ε is the residual strain at each location. r,i Calculate using the following formula: ； Where L 0,i L is the initial spacing between the i-th pair of markers. 1,i The spacing between the i-th pair of markers after processing in S2; ε r,i The larger the absolute value, the higher the residual internal stress at that location before pre-relaxation.

4. The processing method for reducing deformation at garment seams according to claim 1, characterized in that, In S4, the stress compensation coefficient is determined according to the following formula: ； Where K c Let |ε be the stress compensation coefficient. r | represents the absolute value of the residual strain at that location, ε ref For reference residual strain, α is the fabric type coefficient; K c The larger the value, the higher the stress compensation intensity required at that location.

5. The processing method for reducing deformation of garment seams according to claim 4, characterized in that, Reference residual strain ε ref Take the median or average value of the absolute values ​​of residual strain in all marked point pairs; the fabric type coefficient α is obtained through pre-calibration, and the value of α for woven fabrics ranges from 0.8 to 1.2, while the value of α for elastic knitted fabrics ranges from 1.5 to 2.

5.

6. The processing method for reducing deformation at garment seams according to claim 4, characterized in that, In S5, the stitch length P and feed rate F for each curvature section are adjusted according to the following formula: ； ； Where P0 is the reference stitch length for this curvature section, F0 is the reference feed rate for this curvature section, β is the stitch length adjustment coefficient, and γ is the feed rate adjustment coefficient; K c The larger the size, the smaller the stitch length and the smaller the fabric feed.

7. A processing method for reducing deformation at garment seams according to claim 6, characterized in that, The values ​​of the needle spacing adjustment coefficient β and the fabric feed adjustment coefficient γ are both in the range of 0.1 to 0.3, and β > γ.

8. The processing method for reducing deformation of garment seams according to claim 1, characterized in that, In S4, the curvature segment division method includes: dividing the straight segment in the splice seam into the first curvature segment, dividing the inwardly concave arc splice segment into the second curvature segment, and dividing the outwardly convex arc splice segment into the third curvature segment.

9. A processing method for reducing deformation at garment seams according to claim 1, characterized in that, During the sewing process of S5, the feed tension of the upper and lower layers of fabric is maintained within the range of 0 to 5% micro-elongation.

10. A processing method for reducing deformation at garment seams according to claim 1, characterized in that, In S2, the directional stress pre-relaxation treatment is low-temperature steam ironing relaxation, with an ironing temperature of 60°C to 95°C, and the steam action time on the seam area is 3 to 12 seconds, and no tensile force is applied to the seam area during the ironing process.

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