After the sofa fabric is laid out and cut, these fabric blocks need to be sewn together, which we call the sewing process.

1. Sewing method Before the sofa fabric is covered, some fabric pieces need to be sewn together, and if necessary, welts should be added.

（1）. Trial sewing is to temporarily sew two pieces of fabric together. Trial sewing is mainly used to help the positioning of the fabric and facilitate inspection and adjustment. The trial sewing can be sewn with pins or wide stitches. After the formal sewing, the pins or pins of the trial sewing should be removed. suture. For flat stitching, first put the two pieces of fabric together facing each other, try sewing with pins and wide stitches, then formally sew a line about 10mm along the edge, and then remove the pins and threads of the trial sewing. Welt seam, first make two pieces of fabric flat seam, then cut off a part of one seam, and then use the other seam to sew on it, as shown in Figure 8-46, the welt is clamped when sewing the fabric The imported lines are mainly used for cover seams and trim edges. Then patch the head cloth and the handle cloth. Sew the head cloth on the base, backrest and armrest respectively, and press another stitch on the original seam after splicing. The hard edge of the sofa needs to be sewn with handle cloth, the handle cloth is placed on the bottom layer, the middle is the molding line, and the top is the face. In this way, the rule line is straight, and once the handle cloth and the face are nailed flat, the rule line in the middle will come out naturally. Another function of the handle cloth is to position and size the face, so that the outline of the sofa is clear.

（2）. Concealed needles and concealed nails The sutures of concealed needles should not lean on the outside of the sofa surface, and are often used for manual stitching of the exposed parts of the sofa surface. Concealed nails are used for nailing the fabrics with wooden frame parts, and the nail caps are not visible on the surface of the nailed fabrics.

2. The comprehensive sewing process of the seat bag jacket Dark thread, single thread, double thread, etc. are the external visual effects of the fabric joint after sewing. The dark thread means that after the two pieces of fabric are sewn, the seam line is inside, and the seam line cannot be seen outside. ;Single line means that on the basis of the dark line, only one side of the dark line is stitched once, and the double line is based on the dark line, and the two sides of the dark line are stitched once. Before sewing, the fabric should be treated in various ways according to the situation.

（1）. Since the overlock fabric is woven vertically and horizontally, the edge will come off and loose after a long time. Therefore, it is usually necessary to overlock each piece of fabric with an overlock machine first, and then the fabrics are interlocked with each other. Sew up. Leather and artificial leather fabrics do not need hemming. When hemming, control the fabric with both hands, do not swing left and right, and cut off the hemming thread after hemming.

（2）. Shovel leather For some thick leathers, since the edges need to be sewn during sewing, the overlapping of the thick skins on the edges will affect the visual effect. Therefore, sometimes the back of the leather at the seam should be shoveled first with a shoveler, and a rough leather will be used. The grinding wheel sands off part of the inner dermis fibers. The width of the leather edge depends on different requirements, generally 25mm.

（3）. Cotton pressing Align the cut leather or fabric with the fiber cotton, with the leather or fabric on the top and the fiber cotton on the bottom, evenly press it to the sewing machine, and the cotton pressing seam door is 5mm. Because the fiber cotton is soft, the fiber cotton is sewn close to the inner side of the leather and outside the sponge, which can ensure that the sofa is full of vision and soft to the touch. After sewing, use scissors to trim off any excess fiber cotton.

（4）. Splicing Combine the two pieces of leather or cloth with both hands, and send them to the sewing machine by pressure. Make sure that the feeding speed of the upper and lower leather or cloth is the same. Alignment of notches should be checked at all times while sewing to avoid misalignment. The notch is a triangular notch cut on the outer edge of each piece of leather and cloth. If there is no notch, mark the leather surface according to the template and cut it. Since each piece of material is independent, it is difficult to find and align during sewing. Large, so each piece of fabric will have a notch on the edge, and the notch positions of the fabrics sewn together will coincide. When sewing, the edges between the two pieces of fabric should overlap. Generally, there is a sewing width of about 12mm on the periphery of the fabric, and the sewing width of thick leather should be increased to about 20mm.

（5）. For the thick seam at the joint, the crimping line should be cut corners, so as not to affect the frontal visual effect. Be careful not to cut the thread end to avoid the thread coming off. Use both hands to separate and level the skin, hold the skin in one hand, draw the thread in the other hand, and use both hands. Tie with the bottom line of the lifting face. After the thick leather is sewn, the edge needs to be bent. After sewing, it should be cut more intensively at the edge that needs to be bent on the inside to avoid deformation of the front of the leather cover.

（6）. Inspection Check whether the process folds are uniform and symmetrical. Check whether there are jumper lines and obvious floating lines on the leather and cloth parts, whether the lines are straight, smooth, and have no ends, the hidden line seam is between 12~15mm, the double-sided pressure line is separated by 10mm, the seam is centered, and the single-side line distance is 10mm. The seam is 5mm, and the needle distance is 4-6mm. Pay attention to whether the color of the leather cloth is consistent, whether there is obvious color difference, and whether the fabric pattern is symmetrical.