The device of an electric sewing machine. Sewing machine Seagull

Picture 1.Electric drive EP-40-5-03.

Somehow they brought an electric drive EP-40-5-03 from a sewing machine for repair. It is too early to write them off for scrap and they are still quite common. A preliminary autopsy showed that some craftsman was already digging there, and with the help of his “gentle” manipulations, the microassembly 03GP8 available there was cracked in one place, and in another a piece of a corner with applied tracks was broken off from it.

In short - the heart of the electric drive could not be repaired. Searches on the Internet did not give anything, there were no diagrams and tips for repairing such a drive on Google, Yandex and other search engines. I came across only the ENP-40-5 drive circuit (the Chaika machine), made on a quad comparator.

There were two exits; - try to restore the microassembly, - assemble the circuit on the comparator. I decided to go first on the first path, if possible. Of course, there was no mention of restoring the 03GP8 microassembly, since it is not realistic to do this at home, but it is quite possible to try to understand its scheme and understand the principle of operation and can assemble a duplicate on a “loose” one. Here's what happened.

Figure 2.Electric drive control board.

I will not describe in detail what kind of work it took to understand and draw a schematic diagram of a microassembly, I will only say that it was possible to measure the resistance values ​​​​only 3x. The next day I brought a probe for measuring SMD parts in order to measure the containers (there are 3 of them in a microassembly). But on my desktop I no longer found pieces from the disassembled 03GP8, or the cleaning lady put her order there, or ..., in short, there were no pieces and the search in the trash bin also did not give anything, fortunately I managed to sketch everything yesterday.

Figure 3Microassembly 03GP8 (not mine).

The dimensions of the microassembly are about 2x2 cm, it is made on a thin ceramic plate and has 7 leads, of the parts visible on it, only transistors and SMD capacitors are visible, resistors and tracks are deposited by sputtering. In short, it was possible to draw a diagram, where with the help of a magnifying glass, where with guesswork.

Figure 4Microassembly scheme 03GP8, pin numbering from the side of the parts.

When analyzing the general circuit of the electric drive, it was found that the wires from the drive pedal were still mixed up (maybe the first master shoved the wrong place during assembly), that is, with such a combination of switching on the pedal, the circuit will not work. I put everything in its place on the diagram, “piled” the microassembly on loose pieces, on a board of the same size (well, maybe a little more), and proceeded to general tests. All tests are best done with an isolating transformer in order to ensure the safety of yourself and your measuring instruments.

Of course, it could be assembled on SMD elements, but to be honest, I have not worked with them yet, and a piece copy, in short, did not bother.

Figure 5Scheme of the electric drive EP-40-5-03.

I will also say that there is a sensor (alternating voltage generator) on the drive motor, indicated in the photo below - in a circle. The swing of the change on it reaches 12 volts (the frequency depends on the speed). It is intended, as I understand it, to “stretch” the limit of engine speed regulation by the pedal. If you turn it off, then the engine speed is regulated very sharply, and it is almost impossible to catch some stable speed with your foot. The sensor is circled in the figure.

Figure 6Electric motor with sensor.

I put any transistors on the microassembly, the main thing is where you need p-n-p, and where you need n-p-n. A frequency-setting capacitor with a capacity of 0.1 to 0.3 (initially it was set to 0.47 uF), the engine speed depends on it. The electrolyte available on the common board is 10 uF x 16 volts, it makes no sense to increase it, since with its large capacity the engine starts to twitch at the moment the pedal button is closed (when the pedal is pressed). In addition to the microassembly, the board had a flying thyristor and a D815 zener diode, which I also replaced. Thyristor installed VT152.
Yes, I also wanted to say that the conclusions of the microassembly are not at a standard distance from each other, but a little wider. I soldered 6 pins (according to the diagram, it turns out that 5-6 pins are connected, and I connected them on the board), and slightly moved them apart so that they sat in the holes of the board.

Figure 7Analogue 03GP8 assembled.

In short, almost everything went without much difficulty. I figured out everything and drew what should be connected to the board. Below in the figure, the board is shown from the side of the details. The values ​​of the installed elements are affixed, as well as all the necessary connections.
The paths are drawn with reverse side. That is, if you make a print, you will need to mirror the picture.

Figure 8Printed circuit board and wiring diagram.

The general board is also drawn in Sprint Layout 5, attached in the archive, if anyone needs it. The microassembly was soldered without a seal, by hanging mounting. If someone develops it on SMD and shares, I will be very grateful.

P.S.
This microassembly was repeated by some radio amateurs, the reviews are positive.
Sergey Frolov assembled a microassembly on SMD elements and shared his printed circuit board (it was added to the archive, the board is in the Sprint-Layout 6.0 format), here is his design.

Figure 9Microassembly 03GP8 on SMD elements.

Archive for article

Initially, the device of the sewing machine was developed in such a way that it could independently perform work, thereby replacing a person. This invention made it possible to significantly facilitate the work of a seamstress and increase its productivity. The scheme of work allows even an absolute beginner, who has never held a needle in his hands, to sew straight and high-quality stitches. latest generation sews devices not only in a simple way, they are able to create patterns and embroidery. The achievements of modern technology are amazing, but the principle of operation of each sewing machine is still based on the very first algorithm developed many years ago.

There are basic parts of a sewing machine, without which not a single unit can do:

• flywheel;
• winder;
• sleeve;
• sewing platform;
• stitch selection wheel;
• sleeve rack
• receiver (reverse)
• needle holder;
• needle plate;
• foot;
• presser foot raise and lower lever.

But these are the details that are visible on a superficial examination - they are a small fraction of the mechanism hidden under the case. There's a complex system inside to power the shuttle. . We can say that the operation of the sewing machine is entirely based on the shuttle. For an unprepared person, the parts diagram of an ordinary sewing machine may seem complicated and confusing, but everything becomes clear if you understand a little.

The bobbin is the most visible detail with which the tailor constantly interacts. It is located behind retractable panel under the needle. To remove the bobbin from the slot, pull it towards you and slightly up. Thus, you will bend the small grip and release the element.

The bobbin is necessary for the supply of threads, which are wound on it from the main spool before work. This happens automatically - the thread from the spool is threaded into a special hole in the bobbin. After that, the part is placed in the nest, and the spool of thread is fixed on the body of the machine. When the flywheel is activated, the bobbin rotates, which winds the thread on its axis, while the spool of thread also rotates.

To tension the thread during operation, the structure of the bobbin includes small screw. Properly set settings exclude the possibility of skipping the top and bottom stitches. A tailor can sew without being distracted by constant quality checks. Carefully check the thread before starting work, its excessive tension causes permanent breaks. about the ideal thread tension.

A small detail, the so-called spout, designed to insure the coil from accidental loss of the bobbin. It is mounted on a moving panel, which is pressed by a spring mechanism from the sleeve body. If everything works as intended, then the system does not crash. While this item is in correct position, the bobbin is securely fixed in the sewing machine and cannot be pulled out. To reassemble, fold back the spout, and while holding it in this position, insert the bobbin into place.

When examining the body on a sewing machine, you can find an elongated protrusion. Its task is to prevent the rotation of the spool with the bobbin or the shuttle drive.

The bobbin inserted into place interacts with one of the main parts of the device, namely with the shuttle. It is presented in the form of a part passing back and forth, embedded in a special profile.

A working sewing machine sets it in motion by means of connecting rod, which sets the correct trajectory.

The operation of the connecting rod can be controlled by the operator. For this, a retractable metal panel is specially provided on the case. By unscrewing it, you can see how the flywheel rotates, setting in motion the needle, which goes up and down. At the lifting point, not reaching the table surface of five millimeters, a sharp grip passes by it.

This capture is bow of the shuttle. The design of the sewing machine provides for a gap between this nose and the needle, not too large, but not small enough to allow them to accidentally come into contact.

Sometimes the distance starts to increase, and if its value changes even by half a millimeter, then the machine will start skipping stitches in the line. With such a failure, the needle continues its work, the fabric advances regularly, but the thread does not sew it at all. Perforated matter is practically not fastened together and continues its movement. To eliminate this trouble, it is necessary to adjust the position of the needle to the shuttle.

Video about how to adjust the shuttle of the sewing machine from the Podolsk company.

Operation of the sewing machine

How is the sewing machine arranged, and what forces drive its internal processes? The whole system is based on the simplest principle based on a given movement of the needle. Taking the upper thread with her, she threads it down. Then it is picked up by a shuttle that is already ready for this, and intertwines the lower thread with the upper thread.

The simplest movement provides the basis for complex manipulations such as zigzag stitches and even patterned embroidery. Video how to embroider on a home sewing machine.

Manufacturers are improving their models. Today, there are already units with a special addition in the form of a side needle for processing the edges of matter, but it is not easy to find them in ordinary stores.

The inner part of the housing hides a drive, which is operated manually (in mechanical machines) or by means of an electric motor (in electromechanical devices). The engine through the connecting rod starts the rotation of the other three shafts. Going into details, we can say that the system includes one intermediate axle, which transmits a rotational impulse to the three described shafts.

This system is designed for a long period of use and is considered quite durable. To apply lubricants to moving parts, holes are provided in the body, into which the nozzle of the greaser can easily pass.

Mechanisms mechanical sewing machines do not lend themselves to rapid wear, and their characteristics are considered among the best. At proper care the device can serve the tailor up to fifty years, without any problems. However, for this you need to follow all the preparations prescribed by the instructions before work, as well as regularly coat and clean moving parts.

In more advanced models pedal provided, when pressed by the foot on which all mechanisms are set in motion. It is much more convenient to use, as it provides freedom to the hands. Of course, modern designers have improved this system too, turning the pedal from mechanical to electric.

Cloth movement

Speaking about how a home sewing machine works, one cannot omit the description of a device designed to pull fabric. This revolutionary invention for its time made it possible to set the desired stitch length, and also relieved tailors of the obligation to monitor the progress of the flap.

Everything happens as follows:

• at the first stage, the main shaft passes through the central part, which is connected to the flywheel axis through the connecting rod;
• two rods pass in the side parts, during the synchronous rotation of which the broaching mechanism sets in motion.

The first is equipped with a part that experts call among themselves "Dovetail". For a simple person, it is more like a key. This element moves back and forth in the direction of the fabric.

The second axis has a cam, which is located in the dovetail space. Its main function is to raise and lower this part.

The final result of all movements of the listed mechanisms is the operation of the sewing machine, the part in the form of a “dovetail” sets in motion the broach teeth. Having received an impulse, the teeth perform their steps, scrolling in place.

All manipulations to adjust the stitch length are carried out using the rotary lever. A very small piece is fastened to the axis of the tailed key. When the lever is turned, the tails change their configuration from the initial position, which leads to a change in the stitch length in the line. Video Shows you how to properly adjust your stride length.

Thread tension

This manipulation is carried out with special screw located above the needle holder. The tension of the upper thread is an important indicator that controls the quality of the seam. Not far from the needle holder is a special eye that moves during operation and does not allow the tensioned thread to loosen or sag when the needle goes up. Without this little detail, all the work of the sewing machine would come to naught.

Video how to assemble and install the thread tension regulator.

winding device

At the end of the description, a few words should be said about the winding device. As a rule, not far from the flywheel for winding is a small pressure wheel with a shaft equipped with a risk.

On the panel below it, there is an eyelet with another small wheel. The spool is mounted on a vertical stand, and from it the thread is passed over the table to be wound on the bobbin. To ensure proper operation, the pressure wheel is gently pressed with a finger, after which the rotation transmitted from the sewing machine drive begins.

The design provides for another option. If the lower thread suddenly ends, you can use the end taken directly from the needle. Most importantly, do not forget to pull it out of your ear before doing this. After that, repeat the algorithm described above.

Position I. Needle 1, puncturing the fabric, holds the upper thread under the needle plate, when lifting, a loop is formed, while the thread take-up 2 drops to the middle of the slot and feeds the thread.

Position II. The needle rises, and the nose of the shuttle 3 captures the loop and, moving clockwise, expands it. The thread take-up lever, falling down, feeds the thread to the shuttle.

Position III. The hook expands the loop of the upper thread and wraps it around the bobbin. The thread take-up lever, rising up, pulls the thread out of the shuttle set.

Position IV. When the loop of the upper thread wraps more than 180° around the bobbin, the thread take-up lever quickly moves up and tightens the stitch. The shuttle begins to move counterclockwise.

Position V. The teeth of the rack 5 and the foot advance the fabric so that the needle makes its next puncture at a distance equal to the length of the stitch.

Question and task

1. Tell us about the process of formation and interaction of working bodies.
2. What are the features of the thread take-up?

Laboratory and practical work

Reading the kinematic diagram of a sewing machine. Education scheme lockstitch.

1. Task

Look at the pictures on which the mechanisms of the working bodies of the sewing machine are given, and answer the questions:

See picture -

1. What parts are included in this mechanism?
2. Where are they located on the kinematic diagram?
3. How is the movement transmitted from the main shaft, for example, to the shuttle in the shuttle mechanism? (Follow the cinematic diagram.)

2. Exercise:

1. thread the upper and lower threads on the sewing machine and open the sliding plate;
2. slowly rotating the flywheel by hand, follow the process of the formation of a lockstitch;
3. study the work of the working body, which the teacher will indicate, and answer the questions: what is the role of this body in the formation of a stitch? What mechanism does this organ belong to?

"Serving labor", S.I. Stolyarova, L.V. Domnenkova

The rail works with a presser foot, which must press the fabric against the rail over its entire area with a certain force. The presser foot assembly has an adjustable spring for this, as well as parts that lift the foot and lower it onto the fabric. The presser foot can be with a movable sole and with a swivel sole. These paws are comfortable...

The fabric feed mechanism consists of three units: the horizontal movement unit, the vertical movement unit and the presser foot unit. Fabric motor mechanism A - eccentric mechanism, B - cam mechanism, a - tissue motor mechanism, b - kinematic diagram of the mechanism: main shaft, eccentric, stitch regulator, connecting rod-fork, rocker arm, screw, rocking roller, cam, fork, lift shaft , rocker, roller, lever fork, ...

In technology classes in school educational institutions, teachers talk aboutsewing machine device and we are all almost 100% sure that we know how the sewing machine works. However, quite often, we even incorrectly name some parts of the sewing machine, and very few people have a real idea of ​​\u200b\u200bhow the sewing line is formed. If you wishdo the repair yourself , or setting up your sewing machine, when using technical literature for this, you need to know the exact terms and understand the principle of the design and operation of the sewing machine. All machines like those called Zinger, or Podolsk, perform one straight seam with a foot or hand drive and are arranged in almost the same way. And sewing machines such as Chaika 104, 132, 134, 143, 144 differ from them only in the presence of an electric motor and additional operations based on a zigzag stitch. Sewing machines such as Chaika and Podolsk have a vertical swinging hook in their design, and sewing machines produced now (these are Brother, Singer, Janome and many other brands use a more modern design - a horizontal shuttle.

Other models of sewing machines have a vertical double-fit shuttle that rotates. This is used in industrial sewing machines. In addition to the fact that the shuttle has become rotating, new possibilities for eyelet loops and embroidery of patterns of any complexity on fabric have appeared, it is even possible to embroider a photograph. Modern sewing machines come with a wide range of accessories and accessories. And as a novelty, included with some machines, the overlocker, which expands the capabilities of sewing machines, allows you to perform any process related to tailoring.

1. Terminology used to name the parts of a sewing machine.

Screw - this is not a bolt, has a round head, or without it. A thread is cut on the screw shaft, and there is a slot for a screwdriver on top of the screw.

Bolt - this is no longer a screw, it can be turned with a wrench and it has a 6 or 4-sided wrench head corresponding to its size. And of course, the bolt has a thread on the rod.

Shaft - this is a round axis on which parts are fixed to transmit movement to them.

Sleeve - a metal cylinder, with a hole along its axis inside. Used to mount axles and shafts. Instead of bushings, plain ball bearings and oscillating bearings can be used. To transfer the moment of rotation to the shafts located in parallel and spaced at a great distance from each other, belts and belt-gear drives are used.

Crank - located at the end of the rotating shaft. A finger is inserted into it, which secures the connecting rod

connecting rod - a piece of iron with two bushings at the ends - this is the main element for converting the rotation of one shaft into the rotation / rolling of another.

Rail - a part with teeth, it is located under the presser foot, intended to advance the fabric.

Thread take-up - a thin and long wire leader on the front side of the machine. It pulls the thread up when a stitch is formed and prevents the thread from sagging. At the end of it is an eyelet or slot for threading the upper thread.

Needle plate - a metal plate with a slot for the passage of the needle. The plate also has slots for the rack. Needle bar - a pin on which the needle is held and moves it.

Bobbin - a small spool on which the lower thread is wound. It can be metal or plastic.

bobbin case - the main part of the shuttle device, a bobbin is inserted into it.

2. How the lockstitch is formed

A two-thread shuttle stitch is being formed interlacing in the middle of the sewn fabrics or materials. The top thread is called needle thread because it is threaded into the eye of the needle, and the bottom thread is called bobbin thread because it is unwound from a bobbin mounted inside the bobbin case (bobbin mechanism). The lock stitch is not very stretchy compared to the chain stitch. Therefore, the shuttle stitch is not used for sewing knitwear, highly stretchy fabrics. When strong stretching of products sewn with a shuttle stitch, for example tracksuits, the shuttle seam may burst. The advantages of this type of stitching are that it is unravelable and strong enough, both in the longitudinal and transverse directions. The main disadvantage of this line is the frequent replacement of bobbins. The weaving of threads into a stitch is performed using a swinging, rotating, or oscillating shuttle. In household sewing machines, especially old-style sewing machines, an oscillating hook is used, in sewing machines of the latest releases, a horizontal hook is used. In such a hook, the bobbin is visible from the outside. One of the most reliable and fastest is considered a rotating type shuttle; it is used in industrial sewing machines. Stitch formation occurs when the needle, together with the thread, pierces the fabric, begins to move up one and a half to two millimeters. At this moment, an excess of thread is created, and a loop is formed above the eye of the needle, into which the shuttle nose passes. Taking the upper thread with it, the hook rotates it 180 degrees in a circle and at the same time the thread take-up moves up, pulling the upper thread. When the thread crosses the 180 degree mark, the thread take-up pulls the thread out of the material and in this way a stitch is formed. After all this, the feed dog of the machine advances the fabric by the stitch length, to the original one, to form a new cycle. The hook performs two revolutions during the formation of a stitch. One turn turns out to be idle, and the other is working, and all the nodes of the sewing machine (needle, gear rack, thread take-up) work at this time, completing the formation of the stitch. Isn't it brilliant? And for those who still do not understand anything, we offer you to watch our branded video!

Sewing machine device, video:

2. Adjustment of gaps of interaction of a needle and a shuttle.

If you already have an idea about sewing machine device and the process of forming a lockstitch, it will be easier for you to understand how the shuttle knot is set up - interaction of needle and shuttle . From the configuration of this node, depends entirely quality work your sewing machine: skips, tangles, breaks in the upper and lower threads and other bad stitches.

Basic gap settings: At the moment the needle is raised by one and a half to two millimeters, a loop of the upper thread is formed just above the eye of the needle. At the same time, the nose of the shuttle passes almost close by, at a distance of 0.15 mm from the hollow of the needle (a pronounced depression in the needle), and one and a half millimeters above the eye of the needle. These settings are still only an average value and serve only as a guideline for setting up almost any lockstitch sewing machine. Depending on the type of fabric, the parameters may vary. For thick or stretch fabrics, slightly different values ​​\u200b\u200band are set, which are established experimentally. Other mechanisms of the machine also create an influence on the formation of a stitch: a gear rack, a presser foot, bobbins, an upper thread tensioner, a compensation spring, and others. More details about their proper adjustment and repair can be found on our website. In the future, we will publish several more articles on this subject.

Scheme.

All sewing machines are divided into special and universal. Special machines perform only one specific technological operation: sewing buttonholes, sewing on buttons, etc. On universal machines, seams can be sewn various kinds, stitches of different lengths and directions, using special devices, you can make loops, etc.

Working bodies of the sewing machine. The working bodies of the sewing machine are: needle, cloth motor, paw, thread take-up, shuttle.

The work of each working body of the sewing machine is provided by the corresponding mechanism. The formation of a line is ensured by the coordinated work of all mechanisms. They are based on mechanisms for converting rotational motion into reciprocating motion. These conversion mechanisms are: crank, eccentric, cam.

needle mechanism.

The most common converter of the rotational movement of the flywheel and the main shaft into the reciprocating movement of the needle and vice versa is the crank mechanism, which is used in the needle mechanism (Fig. 1).

The tissue engine mechanism (Fig. 2) consists of three nodes: horizontal movement unit, node of vertical movement and presser foot knot.

Eccentric mechanism

The eccentric mechanism consists of eccentric, fork connecting rod and rockers.
The eccentric is rigidly fixed on the shaft and performs a rotational movement, is the leading link. The connecting rod-fork (as in the crank mechanism) oscillates, the connection of the eccentric with the connecting rod and the connecting rod with the rocker arm is movable. The rocker is rigidly fixed on the advance shaft and performs oscillatory movements, it is a driven link.

In the vertical movement unit, a cam mechanism is used, which serves to convert the rotational movement into a complex repetitive movement that occurs in a certain closed cycle. The main part of this mechanism is the cam (there are flat (disk) and cylindrical cams). During oscillatory movements (Fig. 2, b) of the rocking roller 7, the cam 8 presses on the horns of the fork 9, which cover it. The fork rotates together with the lifting shaft 10, which raises the rocker 11, at the end of which there is a roller 12 inserted into the fork of the tissue feed lever 13. When lifting, the lever presses on the upper horn of the fork and lifts it together with the rack. The lift shaft is driven by the main shaft and the oscillating roller, which in turn is driven by the crankshaft through the connecting rod. Its design allows you to adjust the height of the rail, depending on the thickness of the fabric being sewn.

Paw knot.

The process of forming a lockstitch.

Position I. Needle 1, puncturing the fabric, draws the upper thread under the needle plate, when lifting, a loop is formed, while the thread take-up 2 drops to the middle of the slot and feeds the thread.

Position II. The needle rises, and the nose of the shuttle 3 captures the loop and, moving clockwise, expands it. The thread take-up lever, falling down, feeds the thread to the shuttle.

Position III. The hook expands the loop of the upper thread and wraps it around the bobbin. The thread take-up lever, rising up, pulls the thread out of the shuttle set.

Position IV. When the loop of the upper thread wraps more than 180° around the bobbin, the thread take-up lever quickly moves up and tightens the stitch. The shuttle begins to move counterclockwise.

Position V. The teeth of the rail 5 and the foot advance the fabric so that the needle makes its next puncture at a distance equal to the length of the stitch.