Kuike is a professional intelligent automatic sewing machine manufacturer since 2014
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Kuike is a professional intelligent automatic sewing machine manufacturer since 2014
Causes and treatment methods of common faults in lockstitch sewing machines
Jumpers can also be called jumpers. It refers to the phenomenon that the upper thread and the bottom thread are not twisted on the stitches of the sewing material after sewing. The reason is mainly due to the distance, clearance, height difference between the needle and the hook tip.
It is caused by meeting the tolerance accuracy requirements; in addition, it can also be caused by loose parts, wear, or inaccurate positioning of the position.
Jumper phenomenon can be divided into: accidental jumper, intermittent jumper and continuous jumper.
accidental jumper
1. When sewing materials with uneven thickness, due to the use of thinner needles, when encountering thicker parts, the needles are prone to shift, resulting in jumper faults; replace the corresponding thicker needles , sewing
When the thickness of the sewing material is uneven, the sewing speed can be appropriately slowed down
2. Because the back wall of the needle is not orthogonal to the hook, the hook thread hooking effect is not good; properly adjust the orthogonal position of the needle and the hook, and the hook tip is located at the upper part of the needle hole when the needle is hooking the thread on the edge
1.55MM, 0.05MM from the needle groove
3. The quality of the suture is not good and the twist is uneven, resulting in insufficient stability of the coil formation; it can be solved by choosing a reasonable suture, the twist should be appropriate, and the upper thread should be left-twisted
4. When sewing thin materials, the thread take-up spring is not very elastic when the thin thread is wrongly stitched with a thick needle; by changing the needle, the elasticity of the thread take-up spring is reduced.
5. The needle tip is hairy, not sharp or bent; replace the needle
6. For some reason, the tip of the hook becomes convex; the tip of the hook should be properly ground and polished
7. The long-term use of the machine will cause the needle hole of the needle plate to wear more and exceed the tolerance range of the original design; replace the qualified needle plate
8. The pressure of the presser foot is too weak; the pressure of the presser foot should be increased
Intermittent jumper
1. Due to the long-term use of the machine, the high and low positions of the needle bar are displaced, and the wear of the needle bar connecting column, the needle bar connecting rod, the thread take-up crank and other parts will lead to loose clearances and jumpers;
Replace the worn parts, readjust the height of the needle bar, the distance and clearance between the hook and the needle according to the standard
2. It is caused by changing the type of sewing products; the needle and thread must meet the requirements, and the distance between the original hook and the needle should be adjusted reasonably. When sewing heavy materials, increase the presser foot pressure
3. Caused by the incompatibility between the bottom plane of the presser foot and the plane of the needle plate and the tooth surface of the teeth; grind the presser foot and teeth to make the plane of the three parts close or replace the qualified presser foot and teeth
4. The needle is bent; replace it with a new needle
5. The needle is too thin or the suture is too thick; replace the corresponding needle and suture
continuity jumper
1. The thread end of the bottom thread is too short, and the loop cannot cover the bottom thread; take out the hook and pull out the bottom thread by about 10 cm. 2. After long-term use of the machine needle, or improper maintenance or maintenance, the position of the parts changes, and the
Sewing requirements are not met; replace qualified parts as required, adjust the height of the needle bar, the distance and clearance between the needle and the hook tip
3. The upper thread becomes hot due to the heat of the needle; the chemical fiber thread should be cooled by the needle (silicon oil)
4. When sewing special materials, the coil cannot be formed normally; the sewing speed should be slowed down and the smoothness of the upper thread should be increased.
5. Equipped with an automatic thread trimming machine. After thread trimming, the upper thread of the needle is too short and the upper thread is pulled out of the needle eye; adjust the coordination time of the thread trimming cam
6. The presser foot groove is too wide. When the needle-punched cloth is withdrawn, the sewing material moves and affects the coil. In this case, the effect is good when making thin materials; according to the sewing material, move the presser foot to the left, right, or width. Fill the groove with solder, then open a narrower groove, and polish or replace the qualified presser foot
disconnection
Thread breakage is one of the common faults in the sewing process of the machine. For lockstitch machines, thread breakage can generally be divided into broken thread and broken bottom thread.
Section line
1. The edge of the needle hole of the needle has an acute angle or needle groove hair; use or replace a new needle after polishing the needle hole
2. The thread-passing holes of the upper thread are partially brushed, so that the suture is blocked during movement; it can be polished with sand leather or coated with polishing paste for polishing and polishing.
3. Thin thread for sewing thick material; replace the thread accordingly
4. The strength of the suture is too poor; replace the suture
5. The pressure of the thread is too tight, so that the suture is bruised or the drawing thread is broken; the thread clipping mule should be loosened properly
6. The inner groove of the rotary hook has an acute angle, which may damage the suture or break the thread; the rotary hook should be polished inside, and then try to install, or replace the rotary hook with a new one.
7. The positioning hook of the rotary hook and the notch of the shuttle frame are not properly matched; adjust the coordination of the positioning hook of the rotary hook so that the upper thread can pass through smoothly
8. The chemical fiber thread will be fused if the needle is overheated; the chemical fiber thread should be cooled by machine needle or suture (silicone oil)
9. There are burrs and acute angles on the edge of the needle hole in the needle plate, which may damage the suture; the yarn rope and polishing paste can be used to pull it out, but it should not be pulled too large.
10. The position of the needle is wrong; adjust the needle to the correct position
11. The needle is bent; replace it with a new needle
12. The up and down stroke of the needle bar is incorrect, the thread take-up on the needle bar crank and the crank positioning mule nail are not positioned in the groove of the thread take-up crank or the positioning direction is wrong; the wrong positioning direction should be corrected after repositioning
Bottom line
1. The bobbin thread is too full, too loose, and too messy, so that the bottom thread is not flowing smoothly during the sewing process, resulting in thread breakage; the winder can be corrected to make the winding on the bobbin uniform, compact and neat. Can
2. The bobbin is too large or the concentricity of the bobbin is not good, and the operation is inflexible; the appropriate coordination between the bobbin and the bobbin
3. The position of the feed dog is too low, and the distance between the quick opening at the bottom of the feeding dog and the outlet of the bottom thread is too small, so that the bottom thread and the quick opening at the bottom of the tooth have contact friction; adjust the height of the feeding dog reasonably, or remove the feeding dog Use fine sand to smooth the bottom of the teeth
4. The bottom thread opening of the shuttle skin is fast due to wear and tear; replace the shuttle skin with a new one
5. The edge of the hook skin is hairy, and the bottom thread is broken; the edge of the hook skin is not only polished
6. The hook skin and the hook shell do not fit well, there is a gap in the fit, and the tension of the outlet thread is not uniform; adjust the matching gap between the hook hook and the hook shell reasonably, so that the tension of the bottom thread outlet does not change.
float
It is one of the more common sewing failures in the sewing process. According to the symptoms of the fault, it can be roughly divided into: floating bottom, upper thread; towel-shaped floating thread; sometimes floating bottom, upper thread, and sometimes no floating thread.
floating bottom, top thread
1. Due to the improper coordination of the action of the feeding and the needle, the bottom thread and the upper thread are blocked during the weaving process, resulting in a floating thread fault; reasonably adjust the positioning position of the eccentric to solve the problem. Correction requirements: when the needle
Start to stab the material but when the distance from the sewing material is 2-3MM, the feeding of the floating bottom and the feeding of the cloth teeth ends. At this time, it is the positioning position of the eccentric wheel.
2. If the tension of the upper thread is too large, the upper thread will float. On the contrary, if the tension of the bottom thread is too large, the bottom thread will float.
Floating upper thread: It can be solved by adjusting the tension of small upper thread; floating bottom thread: can be solved by adjusting the tension of large upper thread
;You can also adjust the tension of the bottom thread to solve
towel float
1. Because the hook is damaged by external force, there are cracks or burrs in various parts of the hook thread, so that the upper thread cannot pass smoothly, resulting in the failure of the towel-shaped floating thread; the hook should be checked, adjusted or replaced
2. When the upper thread gripper fails to operate or the presser foot presses the sewing material for sewing, the thread release hook and thread release top are out of order. As a result, the upper thread is sewn without tension, the upper thread cannot be tightened, and a small amount of remaining thread remains under the sewing material. The retractable in and out position of the thread release nail and the in and out position of the thread clamp can be adjusted reasonably.
Make the thread release nail flexible and flexible, so that the thread clamp can not only release the thread, but also press the thread.
3. Due to the serious rust or burr on the arc surface of the sock dome, it will float and not float during the sewing process; fine sand skin can be used to polish the rust or burr at the arc, and Polishing to a certain degree of smoothness, so that there is no obvious obstruction when the surface line passes through
4. The clearance between the rotary hook and the rotary hook positioning hook is too small, and the assembly is not in place, resulting in the thread not coming out; there is a certain gap between the groove of the rotary hook and the end face of the positioning hook. The thin material machine is about 0.6mm, and the thick material The machine is about 0.8mm, and the two sides should be able to control the rotary hook not to rotate, but also to exit the thread smoothly
sometimes float, sometimes not float
1. Due to the poor coordination between the bobbin and the bobbin, the bottom thread is unevenly discharged, so that it will not float when it occurs during the sewing process; it can be solved by choosing a bobbin with a better fit.
2. The flatness of the outer circle of the shuttle and the hook is not good, so that the pressure of the thread at different outlet positions is also different, resulting in good and bad times when the thread is out.
Different outlet positions are required, and the outlet pressure is basically the same
3. The thread outlet groove under the presser foot presser is too shallow or too short, which will cause the stitches to be affected by frictional resistance when moving forward, making the bottom and upper threads interlaced unevenly; the presser foot should be removed and pulled with fine sand leather The outlet groove under the bottom plate of the presser foot should be polished, so that the sewing material can pass smoothly when it moves forward.
4. The coordination of needles, sutures and sewing materials does not meet the requirements; choose reasonable needles and sutures according to the sewing materials
5. The thin seam is normal, and there is a floating line at the thick seam; the loose thread nail is too long and needs to be shortened a little, and the thread clamping adjustment seat can also be moved slightly outward. However, after the presser foot is lifted and locked, it should be able to loosen the thread. The stitches are skewed
Skewing stitches means that each stitch on the seam is arranged diagonally.
The twisting point of the bottom and top threads is always on one side.
1. The tension of the upper thread is too large; weaken the tension of the upper thread
2. When sewing thin and fine materials, use thick thread so that the kink point of the bottom thread cannot be hidden in the middle of the sewing material; when sewing thin and fine materials, use a softer thread
3. The needle is too thick and the thread is too thin, causing the stitches to be skewed; use an appropriate needle or thread instead
4. The needle is not installed correctly; correct the wrong needle direction
5. The needle bar thread hole is too large; use a needle bar with a small hole to thread the thread
6. The feeding dog is loose or the feeding dog is not parallel to the needle plate groove; tighten the feeding dog or adjust the feeding dog to make the gap between the feeding dog and the edge of the needle plate groove uniform
seam shrinkage
Seam shrinkage refers to the shrinkage of the seam at the seam. If you pull the sewing material hard, the stitches will be pulled off section by section.
1. The bottom thread tension is too large; weaken the bottom thread tension
2. The feeding movement is faster than the needle bar; adjust to the standard
3. The feed dog is inclined; adjust the feed dog to front high and back low
4. The hook and needle plate are not smooth at the thread take-up plate of the thread board; make the thread passage smooth
5. The needle hole of the needle plate is too large; replace the needle plate with a new one
6. The tension of the thread take-up spring is too strong; weaken the tension of the thread take-up spring
Dislocation of upper and lower sewing materials
During the sewing process, sometimes the upper layer and the lower layer of sewing material are misaligned. This is caused by long-term wear of the feeding mechanism or loose and misplaced parts.
1. The pressure of the presser foot is too large, causing the lower sewing material to dislocate; reduce the pressure of the presser foot
2. The feeding dog is inclined; adjust the feeding dog to front high and back low
3. The cloth feeding movement is slower than the needle bar, which causes the sewing material to be dislocated; advance the feeding dog action
4. The feeding force is not uniform; coarse tooth feeding teeth can be used
5. The surface of the bottom of the presser foot is rough; the surface of the bottom of the presser foot is polished and polished
6. The artificial leather sewing material has a certain adhesiveness; a small amount of oil or other lubricants can be applied to the surface
Poor thread trimming
In a lockstitch machine equipped with automatic thread trimmer, sometimes the upper thread is continuously cut (the bottom thread can be cut), or the bottom thread is continuously cut.
1. The installation of the needle is not good; the movement of the thread take-up spring is too large; the position of the hook is not adjusted properly; the needle is installed correctly, and the bent needle is replaced; tune again
Matching of the full hook and the needle
2. The rotary hook is not selected according to the regulations, and the position of the bottom thread is unstable when the thread is trimmed; check the inner groove of the rotary hook or replace it with a new one
3. The blades of the moving scissors and the static scissors are loose, and the cutting is continuous when the thread is trimmed. The angle, position, and edge of the static scissors do not work well with the moving scissors, resulting in the scissors not being sharp; remove the needle plate and push the
Scissors, and then use three 50# cotton threads to try to cut them together. If the cutting continues, you should (1) grind the blades of the static scissors; (2) correct the inclination of the front end of the static scissors; (3) adjust the position of the static scissors again
4. The left and right positions of the scissors action shaft and the thread trimming cam are not adjusted properly, resulting in insufficient retraction of the scissors; adjust the retraction amount of the scissors to about 2-2.5mm, and adjust the position of the trimmer cam accordingly.
5. There is no quick opening at the end of the fixed knife; oil and oil grind the quick opening or replace the fixed blade with a new one
6. There is no quick opening at the cutting hole of the moving knife; replace the moving knife with a new one
broken needle
It means that the needle is broken by unexpected resistance and obstacles during the sewing process.
The main reason is that the needle collides or rubs against some parts during the working process. in contact with the needle
There are obvious traces of being rolled and rubbed on the machine parts.
accidental needle break
1. When sewing thick and thick materials, the needle is too thin, so that when the needle moves up and down, the vertical position of the needle will shift left and right; choose a needle suitable for the sewing material
2. The needle is bent, the needle tip is hairy, and the screw of the support needle is not tightened; tighten the screw of the support needle and replace it with a new needle
3. When sewing thick and thin uneven sewing materials, the machine speed is too fast, the needle is displaced, and it collides with the hook and is broken; the sewing speed should be slowed down
4. During the sewing process, pushing and pulling the sewing material forcefully will cause the needle to bend and break, as well as the uncoordinated movement of hands and feet; use the machine correctly in accordance with the operating procedures
Continuous needle break
1. The presser foot plate groove is seriously skewed, the presser foot fastening screw is not tightened, the concentricity between the needle plate hole and the needle is poor, and the axial clearance of the lower shaft is too large; adjust the position and clearance of each component reasonably.
Needle
For machines with poor concentricity with the needle plate, adjust the position of the needle plate or tap the lower end of the needle bar after the needle is raised to the position to correct the position
2. Since the plane of the tip of the hook is lower than the plane of the needle-accommodating groove of the shuttle frame; the plane of the needle-accommodating groove is 0.15mm lower than the plane of the tip of the hook or the same level, so that the needle-accommodating groove of the shuttle frame can not touch the needle, but also Act as a needle guard
3. The clearance, spacing, and height of the hook and the needle are incorrect; adjust them reasonably according to the standard
4. The movement time position of the feed dog and the needle bar is wrong. When the needle is punctured, the feed dog is still feeding material, resulting in broken needle; the position of the eccentric wheel can be adjusted reasonably according to the requirements. When the needle is still 2- When 3mm, the feeding dog should finish feeding.
Gauge failure
1. Due to the loose fit between the taper surface and the taper hole of the small top screw on the feed shaft, the stitch length is generated; remove the feed shaft and re-adjust the fitting clearance of the feed shaft&
2. Due to the *-shaped cloth feed rod, the matching gap between the eccentric wheel ferrule and the feeding tooth-lifting eccentric wheel is too large; The stitch length is long and short; it can be adjusted reasonably according to the position of the loose parts
heavy machine
1. The axial planes of the upper shaft, vertical shaft and lower shaft have no gap or no gap on one side, which makes the rotational force of the machine too large; check the axial plane matching of the three shafts. It is required that there is a gap in the plane matching, but not greater than 0.04mm, easy to turn
2. The thread take-up crank and the thread take-up connecting rod pin of the thread take-up rod assembly have no clearance or unilateral clearance in the axial direction, so that the machine has a large turning power; no obvious resistance
3. The clearance between the parts of the tooth-lifting and cloth-feeding mechanisms is too small, which results in a large turning force of the machine; check the clearance between the parts and make reasonable adjustments
4. There are backlogs such as fluff and piles between the top of the feeding dog (the part below the needle plate) and the needle plate; remove the needle plate and the backlog on the feeding dog
5. There are sundries in the rotary hook (the thread is rolled and the thread is broken after the thread is broken); the sundries in the rotary hook should be added, and some sewing machine oil should be added.
6. After the exchange-type correction parts, the turning force of the machine is large; the quality of the parts is not good, such as the concentricity, straightness, and parallelism are not good. Measure or replace a part for comparison
7. The matching clearance of the bevel gear is too tight; properly adjust the meshing clearance of the bevel gear
noise
1. The tooth surfaces of the bevel gears are meshed at different heights, causing noise when the gears are running at high speed; loosen the bevel gear fastening screws with different meshing heights on the tooth surfaces, and loosen the shaft sleeves that are in contact with the bevel gear shaft. screw, tap the high and low positions of the spur gear surface with a knock bar, and then tighten the fastening screws of the bevel gear and the shaft sleeve respectively
2. The sound is caused by the axial loosening of the upper shaft, vertical shaft and lower shaft; the two fastening screws of the gear should be loosened, and the axial clearance of the vertical shaft and the upper and lower shafts should be readjusted.
3. The meshing clearance of the bevel gear tooth surface is too large or too small, resulting in a sound failure; it can be corrected by tapping the sleeve.
Generally, the meshing clearance of a pair of gears is between 0.20-0.40mm
4. After the above three adjustment gears, the sound is not ideal; you can add a small amount of grinding paste on the two pairs of meshing tooth surfaces, and turn the upper wheel forward and reverse by hand, about 10-15min. Use gasoline to clean the dirt, add a little lubricating oil, and then adjust the gap as required
5. The rotary hook is seriously worn, and the matching clearance is large; the axial clearance between the rotary hook and the shuttle frame is 0.07mm, the radial clearance is less than 0.02mm, and the circumferential clearance is less than 0.15mm. At the same time, pay attention to the normal oil supply of the rotary hook
6. The parts are seriously worn and the matching clearance is large; the machine should be adjusted
jumper
Jumpers can also be called jumpers. It refers to the phenomenon that the upper thread and the bottom thread are not twisted on the stitches of the sewing material after sewing.
The reason is mainly due to the distance, clearance, height difference between the needle and the hook tip.
It is caused by meeting the tolerance accuracy requirements; in addition, it can also be caused by loose parts, wear, or inaccurate positioning of the position. Jumper phenomenon can be divided into: accidental jumper, intermittent jumper and continuous jumper.
accidental jumper
1. When sewing materials with uneven thickness, due to the use of thinner needles, when encountering thicker parts, the needles are prone to shift, resulting in jumper faults; replace the corresponding thicker needles , when sewing materials with uneven thickness, the sewing speed can be appropriately slowed down
2. Because the back wall of the needle is not orthogonal to the hook, the hook thread hooking effect is not good; properly adjust the orthogonal position of the needle and the hook, and the hook tip is located at the upper part of the needle hole when the needle is hooking the thread on the edge
1.55MM, 0.05MM from the needle groove
3. The quality of the suture is not good and the twist is uneven, resulting in insufficient stability of the coil formation; it can be solved by choosing a reasonable suture, the twist should be appropriate, and the upper thread should be left-twisted
4. When sewing thin materials, the thread take-up spring is not very elastic when the thin thread is wrongly stitched with a thick needle; by changing the needle, the elasticity of the thread take-up spring is reduced.
5. The needle tip is hairy, not sharp or bent; replace the needle
6. For some reason, the tip of the hook becomes convex; the tip of the hook should be properly ground and polished
7. The long-term use of the machine will cause the needle hole of the needle plate to wear more and exceed the tolerance range of the original design; replace the qualified needle plate
8. The pressure of the presser foot is too weak; the pressure of the presser foot should be increased
Intermittent jumper
1. Due to the long-term use of the machine, the high and low positions of the needle bar are displaced, coupled with the wear of the needle bar connecting column, the needle bar connecting rod, the thread take-up crank and other parts, the gaps that appear are loose, and jumpers appear; the wear and tear should be replaced. the parts, readjust the height of the needle bar, the distance and clearance between the hook and the needle according to the standard
2. It is caused by changing the type of sewing products; the needle and thread must meet the requirements, and the distance between the original hook and the needle should be adjusted reasonably.
When sewing heavy materials, increase the presser foot pressure
3. Caused by the incompatibility between the bottom plane of the presser foot and the plane of the needle plate and the tooth surface of the teeth; grind the presser foot and teeth to make the plane of the three parts close or replace the qualified presser foot and teeth
4. The needle is bent; replace it with a new needle
5. The needle is too thin or the suture is too thick; replace the corresponding needle and suture
continuity jumper
1. The thread end of the bottom thread is too short, and the loop cannot cover the bottom thread; take out the hook and pull out the bottom thread by about 10 cm. 2. After long-term use of the machine needle, or improper maintenance or maintenance, the position of the parts changes and the seam cannot be reached. Replace the qualified parts as required, adjust the height of the needle bar, the distance and clearance between the needle and the hook tip
3. The upper thread becomes hot due to the heat of the needle; the chemical fiber thread should be cooled by the needle (silicon oil)
4. When sewing special materials, the coil cannot be formed normally; the sewing speed should be slowed down and the smoothness of the upper thread should be increased.
5. Equipped with an automatic thread trimming machine. After thread trimming, the upper thread of the needle is too short and the upper thread is pulled out of the needle eye; adjust the coordination time of the thread trimming cam
6. The presser foot groove is too wide. When the needle-punched cloth is withdrawn, the sewing material moves and affects the coil. In this case, the effect is good when making thin materials; according to the sewing material, move the presser foot to the left, right, or width. Fill the groove with solder, then open the narrower groove, and polish or replace the qualified presser foot
disconnection
Thread breakage is one of the common faults in the sewing process of the machine. For lockstitch machines, thread breakage can generally be divided into broken thread and broken bottom thread.
Section line
1. The edge of the needle hole of the needle has an acute angle or needle groove hair; use or replace a new needle after polishing the needle hole
2. The thread-passing holes of the upper thread are partially brushed, so that the suture is blocked during movement; it can be polished with sand leather or coated with polishing paste for polishing and polishing.
3. Thin thread for sewing thick material; replace the thread accordingly
4. The strength of the suture is too poor; replace the suture
5. The pressure of the thread is too tight, so that the suture is bruised or the drawing thread is broken; the thread clipping mule should be loosened properly
6. The inner groove of the rotary hook has an acute angle, which may damage the suture or break the thread; the rotary hook should be polished inside, and then try to install, or replace the rotary hook with a new one.
7. The positioning hook of the rotary hook and the notch of the shuttle frame are not properly matched; adjust the coordination of the positioning hook of the rotary hook so that the upper thread can pass through smoothly
8. The chemical fiber thread will be fused if the needle is overheated; the chemical fiber thread should be cooled by machine needle or suture (silicone oil)
9. There are burrs and acute angles on the edge of the needle hole in the needle plate, which may damage the suture; the yarn rope and polishing paste can be used to pull it out, but it should not be pulled too large.
10. The position of the needle is wrong; adjust the needle to the correct position
11. The needle is bent; replace it with a new needle
12. The up and down stroke of the needle bar is incorrect, the thread take-up on the needle bar crank and the crank positioning mule nail are not positioned in the groove of the thread take-up crank or the positioning direction is wrong; the wrong positioning direction should be corrected after repositioning
Bottom line
1. The bobbin thread is too full, too loose, and too messy, so that the bottom thread is not flowing smoothly during the sewing process, resulting in thread breakage; the winder can be corrected to make the winding on the bobbin uniform, compact and neat. Can
2. The bobbin is too large or the concentricity of the bobbin is not good, and the operation is inflexible; the appropriate coordination between the bobbin and the bobbin
3. The position of the feed dog is too low, and the distance between the quick opening at the bottom of the feeding dog and the outlet of the bottom thread is too small, so that the bottom thread and the quick opening at the bottom of the tooth have contact friction; adjust the height of the feeding dog reasonably, or remove the feeding dog Use fine sand to smooth the bottom of the teeth
4. The bottom thread opening of the shuttle skin is fast due to wear and tear; replace the shuttle skin with a new one
5. The edge of the hook skin is hairy, and the bottom thread is broken; the edge of the hook skin is not only polished
6. The hook skin and the hook shell do not fit well, there is a gap in the fit, and the tension of the outlet thread is not uniform; adjust the matching gap between the hook hook and the hook shell reasonably, so that the tension of the bottom thread outlet does not change.
float
It is one of the more common sewing failures in the sewing process. According to the symptoms of the fault, it can be roughly divided into: floating bottom, upper thread; towel-shaped floating thread; sometimes floating bottom, upper thread, and sometimes no floating thread.
floating bottom, top thread
1. Due to the improper coordination of the action of the feeding and the needle, the bottom thread and the upper thread are blocked during the weaving process, resulting in a floating thread fault; reasonably adjust the positioning position of the eccentric to solve the problem. Correction requirements: when the needle
Start to stab the material but when the distance from the sewing material is 2-3MM, the feeding of the floating bottom and the feeding of the cloth teeth ends. At this time, it is the positioning position of the eccentric wheel.
2. If the tension of the upper thread is too large, the upper thread will float. On the contrary, if the tension of the bottom thread is too large, the bottom thread will float. Floating upper thread: It can be solved by adjusting the tension of the small upper thread; floating bottom thread: it can be solved by adjusting the tension of the upper thread; it can also be solved by adjusting the tension of the lower thread
towel float
1. Because the hook is damaged by external force, there are cracks or burrs in various parts of the hook thread, so that the upper thread cannot pass smoothly, resulting in the failure of the towel-shaped floating thread; the hook should be checked, adjusted or
Change
2. When the upper thread gripper fails to operate or the presser foot presses the sewing material for sewing, the thread release hook and thread release top are out of order. As a result, the upper thread is sewn without tension, the upper thread cannot be tightened, and a small amount of remaining thread is left.
under the seam.
The retractable in and out position of the thread release nail and the in and out position of the thread clamp can be adjusted reasonably. Make the thread release nail flexible and flexible, so that the thread clamp can not only release the thread, but also press the thread.
When the presser foot lifts about 5mm, the thread is released, and when the presser foot presses the sewing material, it acts as a thread presser
3. Due to the serious rust or burr on the arc surface of the sock dome, it will float and not float during the sewing process; fine sand skin can be used to polish the rust or burr at the arc, and Polished to reach
A certain degree of finish is required, so that there is no obvious obstruction when the upper thread passes through
4. The clearance between the rotary hook and the rotary hook positioning hook is too small, and the assembly is not in place, resulting in the thread not coming out; there is a certain gap between the groove of the rotary hook and the end face of the positioning hook. The thin material machine is about 0.6mm, and the thick material
The machine is about 0.8mm, and the two sides should be able to control the rotary hook not to rotate, but also to exit the thread smoothly
sometimes float, sometimes not float
1. Due to the poor coordination between the bobbin and the bobbin, the bottom thread is unevenly discharged, so that it will not float when it occurs during the sewing process; it can be solved by choosing a bobbin with a better fit.
2. The smoothness of the fit of the shuttle skin and the outer circle of the shuttle is not good, so that the pressure of the thread at different outlet positions is also different, resulting in good and bad times when the thread is discharged; reasonably adjust the smoothness of the fit of the shuttle skin and the external circle of the shuttle, and require Different outlet positions, the outlet pressure is basically the same
3. The thread outlet groove under the presser foot presser is too shallow or too short, which will cause the stitches to be affected by frictional resistance when moving forward, making the bottom and upper threads interlaced unevenly; the presser foot should be removed and pulled with fine sand leather The outlet groove under the bottom plate of the presser foot should be polished, so that the sewing material can pass smoothly when it moves forward.
4. The coordination of needles, sutures and sewing materials does not meet the requirements; choose reasonable needles and sutures according to the sewing materials
5. The thin seam is normal, and there is a floating line at the thick seam; the loose thread nail is too long and needs to be shortened a little, and the thread clamping adjustment seat can also be moved slightly outward. However, after the presser foot is lifted and locked, it should be able to release the thread.
The stitches are skewed
Skewing stitches means that each stitch on the seam is arranged diagonally.
The twisting point of the bottom and top threads is always on one side.
1. The tension of the upper thread is too large; weaken the tension of the upper thread
2. When sewing thin and fine materials, use thick thread so that the kink point of the bottom thread cannot be hidden in the middle of the sewing material; when sewing thin and fine materials, use a softer thread
3. The needle is too thick and the thread is too thin, causing the stitches to be skewed; use an appropriate needle or thread instead
4. The needle is not installed correctly; correct the wrong needle direction
5. The needle bar thread hole is too large; use a needle bar with a small hole to thread the thread
6. The feeding dog is loose or the feeding dog is not parallel to the needle plate groove; tighten the feeding dog or adjust the feeding dog to make the gap between the feeding dog and the edge of the needle plate groove uniform
seam shrinkage
Seam shrinkage refers to the shrinkage of the seam at the seam. If you pull the sewing material hard, the stitches will be pulled off section by section.
1. The bottom thread tension is too large; weaken the bottom thread tension
2. The feeding movement is faster than the needle bar; adjust to the standard
3. The feed dog is inclined; adjust the feed dog to front high and back low
4. The hook and needle plate are not smooth at the thread take-up plate of the thread board; make the thread passage smooth
5. The needle hole of the needle plate is too large; replace the needle plate with a new one
6. The tension of the thread take-up spring is too strong; weaken the tension of the thread take-up spring
Dislocation of upper and lower sewing materials
During the sewing process, sometimes the upper layer and the lower layer of sewing material are misaligned. This is caused by long-term wear of the feeding mechanism or loose and misplaced parts.
1. The pressure of the presser foot is too large, causing the lower sewing material to dislocate; reduce the pressure of the presser foot
2. The feeding dog is inclined; adjust the feeding dog to front high and back low
3. The cloth feeding movement is slower than the needle bar, which causes the sewing material to be dislocated; advance the feeding dog action
4. The feeding force is not uniform; coarse tooth feeding teeth can be used
5. The surface of the bottom of the presser foot is rough; the surface of the bottom of the presser foot is polished and polished
6. The artificial leather sewing material has a certain adhesiveness; a small amount of oil or other lubricants can be applied to the surface
Poor thread trimming
In a lockstitch machine equipped with automatic thread trimmer, sometimes the upper thread is continuously cut (the bottom thread can be cut), or the bottom thread is continuously cut.
1. The installation of the needle is not good; the movement of the thread take-up spring is too large; the position of the hook is not adjusted properly; the needle is installed correctly, and the bent needle is replaced; Adjust the fit of the hook and the needle again
2. The rotary hook is not selected according to the regulations, and the position of the bottom thread is unstable when the thread is trimmed; check the inner groove of the rotary hook or replace it with a new one
3. The blades of the moving scissors and the static scissors are loose, and the cutting is continuous when the thread is trimmed. The angle, position, and bevel of the static scissors do not work well with the moving scissors, resulting in the scissors not being sharp; remove the needle plate, push the moving scissors by hand, and use three 50# cotton threads to try to cut them together. 1) Grinding the static scissors; (2) Correcting the inclination of the front end of the static scissors; (3) Adjusting the position of the static scissors again
4. The left and right positions of the scissors action shaft and the thread trimming cam are not adjusted properly, resulting in insufficient retraction of the scissors; adjust the retraction amount of the scissors to about 2-2.5mm, and adjust the position of the trimmer cam accordingly.
5. There is no quick opening at the end of the fixed knife; oil and oil grind the quick opening or replace the fixed blade with a new one
6. There is no quick opening at the cutting hole of the moving knife; replace the moving knife with a new one
broken needle
It means that the needle is broken by unexpected resistance and obstacles during the sewing process. The main reason is that the needle collides or rubs against some parts during the working process.
Obvious traces of being rolled and rubbed can be found on the parts that collide with the needle.
accidental needle break
1. When sewing thick and thick materials, the needle is too thin, so that when the needle moves up and down, the vertical position of the needle will shift left and right; choose a needle suitable for the sewing material
2. The needle is bent, the needle tip is hairy, and the screw of the support needle is not tightened; tighten the screw of the support needle and replace it with a new needle
3. When sewing thick and thin uneven sewing materials, the machine speed is too fast, the needle is displaced, and it collides with the hook and is broken; the sewing speed should be slowed down
4. During the sewing process, pushing and pulling the sewing material forcefully will cause the needle to bend and break, as well as the uncoordinated movement of hands and feet; use the machine correctly in accordance with the operating procedures
Continuous needle break
1. The presser foot plate groove is seriously skewed, the presser foot fastening screw is not tightened, the concentricity between the needle plate hole and the needle is poor, and the axial clearance of the lower shaft is too large; adjust the position and clearance of each component reasonably. For machines with poor concentricity between the needle and the needle plate, adjust the position of the needle plate or tap the lower end of the needle bar to correct the position after the needle is raised to the position.
2. Since the plane of the tip of the hook is lower than the plane of the needle-accommodating groove of the shuttle frame; the plane of the needle-accommodating groove is 0.15mm lower than the plane of the tip of the hook or the same level, so that the needle-accommodating groove of the shuttle frame can not touch the needle, but also Act as a needle guard
3. The clearance, spacing, and height of the hook and the needle are incorrect; adjust them reasonably according to the standard
4. The movement time position of the feed dog and the needle bar is wrong. When the needle is punctured, the feed dog is still feeding material, resulting in broken needle; the position of the eccentric wheel can be adjusted reasonably according to the requirements. When the needle is still 2- When 3mm, the feeding dog should finish feeding.
Gauge failure
1. Due to the loose fit between the taper surface and the taper hole of the small top screw on the feed shaft, the stitch length is generated; remove the feed shaft and re-adjust the fitting clearance of the feed shaft
2. Due to the *-shaped cloth feed rod, the matching gap between the eccentric wheel ferrule and the feeding tooth-lifting eccentric wheel is too large; The stitch length is long and short; it can be adjusted reasonably according to the position of the loose parts
heavy machine
1. The axial planes of the upper shaft, vertical shaft and lower shaft have no gap or no gap on one side, which makes the rotational force of the machine too large; check the axial plane matching of the three shafts. It is required that there is a gap in the plane matching, but not greater than 0.04mm, easy to turn
2. The thread take-up crank and the thread take-up connecting rod pin of the thread take-up rod assembly have no clearance or unilateral clearance in the axial direction, so that the machine has a large turning power; no obvious resistance
3. The clearance between the parts of the tooth-lifting and cloth-feeding mechanisms is too small, which results in a large turning force of the machine; check the clearance between the parts and make reasonable adjustments
4. There are backlogs such as fluff and piles between the top of the feeding dog (the part below the needle plate) and the needle plate; remove the needle plate and the backlog on the feeding dog
5. There are sundries in the rotary hook (the thread is rolled and the thread is broken after the thread is broken); the sundries in the rotary hook should be added, and some sewing machine oil should be added.
6. After the exchange-type correction parts, the turning force of the machine is large; the quality of the parts is not good, such as the concentricity, straightness, and parallelism are not good. Measure or replace a part for comparison
7. The matching clearance of the bevel gear is too tight; properly adjust the meshing clearance of the bevel gear
noise
1. The tooth surfaces of the bevel gears are meshed at different heights, causing noise when the gears are running at high speed; loosen the bevel gear fastening screws with different meshing heights on the tooth surfaces, and loosen the shaft sleeves that are in contact with the bevel gear shaft. screw, tap the high and low positions of the spur gear surface with a knock bar, and then tighten the fastening screws of the bevel gear and the shaft sleeve respectively
2. The sound is caused by the axial loosening of the upper shaft, vertical shaft and lower shaft; the two fastening screws of the gear should be loosened, and the axial clearance of the vertical shaft and the upper and lower shafts should be readjusted.
3. The meshing clearance of the bevel gear tooth surface is too large or too small, resulting in a sound failure; it can be corrected by tapping the sleeve. Generally, the meshing clearance of a pair of gears is between 0.20-0.40mm
4. After the above three adjustment gears, the sound is not ideal; you can add a small amount of grinding paste on the two pairs of meshing tooth surfaces, and turn the upper wheel forward and reverse by hand, about 10-15min.
Clean the dirt with gasoline, add a little
Lubricating oil, and then adjust the clearance as required
5. The rotary hook is seriously worn, and the matching clearance is large; the axial clearance between the rotary hook and the shuttle frame is 0.07mm, the radial clearance is less than 0.02mm, and the circumferential clearance is less than 0.15mm. At the same time, pay attention to the normal oil supply of the rotary hook
6. The parts are seriously worn and the matching clearance is large; the machine should be adjusted