How to make a table loom with your own hands? Design features of STB machines. justification for the chosen direction of work Weaving machine STB 220 technical characteristics

Classification. Shuttleless weaving looms with small-sized weft inserters of the STB type are designed for the production of cotton, wool, silk and linen fabrics. Depending on the design of individual mechanisms and other characteristics, they are divided into the following groups:

narrow- with working widths 175 (180) cm and 216 (220) cm and wide - with working widths 250, 330 and 360 cm;

with single-color and multi-color weft device; the number of colors or types of weft threads that can be simultaneously processed on STB machines is 4-6;

eccentric, carriage and jacquard. On eccentric machines of this type, it is possible to produce fabrics of main and many types of finely patterned weaves, having a weft repeat of no more than 8 threads, with a number of heddles of up to 10. Installation of carriage shedding mechanisms allows you to produce fabrics with a weft repeat of up to 300 and a number of heddles of up to 18;

one-, two- and three-panel. On machines with a reed width of 175 (180) cm, fabrics are produced into one sheet. On machines with a working width of 216 (220) cm and 250 cm, it is possible to produce one or two pieces of fabric. A batch of STB-220 machines was produced, designed to produce three sheets for waffle towels. STB machines with a reed filling width of 330 cm in all industries textile industry used as two- or three-panel. On all STB machines, > except for the STB-175 (180) machine, they work from two beams, and on this machine - from one. One beam is sometimes used on machines with a width of 216 (220) and 250 cm;

with a combat start angle of 140 and 105°(the position of the main shaft at the moment the layer takes off from the weft fighting box). Machines with a reed width of 175 (180) to 216 (220) cm have an engagement angle of 140°, machines with a width of 250 and 330 cm - 105°. On machines with the same starting angle, all mechanisms of the same name operate according to common cyclic diagrams. STB machines, currently mass-produced, are designed mainly for the production of fabrics with medium thread tension.

The process of fabric formation on STB looms is similar to its formation on shuttle looms, only the method of introducing the weft thread into the shed has been changed.

The warp threads 2, unwinding from the beam 1, go around the moving rock 4, pass over the rock pipe 5, through the lamellas of the warp 6, the heddles of the heddles 7, the teeth of the reed 8 and between the teeth of the guide comb of the beam 9. Thanks to the rise and lowering of the healds, the warp threads form a shed, into which the weft thread is inserted using small-sized weft inserters. The laid thread is nailed to the edge of the fabric with a reed 8. The formed fabric 11, having passed the cribs and the fabric support 10, goes around the breast 12, the felt 14, the pressure roller 13 and the squeezing roller 15 and is wound onto the product roller 16.

When producing heavy fabrics, the warp threading pattern is changed, for which an additional fixed rock is installed. In these machines, laying the weft thread into the shed is carried out by small-sized inserters (the number of inserters involved in this process depends on the filling width of the machine), which are fundamentally different from conventional shuttles, since they do not carry weft packages.

STB machines have the following main mechanisms that provide technological process weaving.

The votive consists of two cast iron frames connected to each other by a box-shaped hollow connection. An additional link, made of I-rolled steel, is rigidly connected to the frames of the machine and serves as a support for fastening the down collection chute and the middle bracket of the beams. The under-rock pipe is firmly connected to the frames with clamps and brackets and imparts rigidity to the frame.

The drive transmits movement from an individual electric motor to the main shaft of the machine and ensures reliable stopping of the machine. The transmission of motion is carried out by four V-belts on two pulleys. The drive consists of an activation mechanism, a clutch mechanism, a brake and a roller lock. Starting and stopping the machine is carried out using the starting handles on the side of the chest and the beams. Stopping can be done using the button and from the control device.

The warp release and tension mechanism is designed to regulate the tension of the warp threads and feed depending on the tension value. The machine is equipped with a negative type tension regulator. The base is supplied automatically. The tension is adjusted by a moving rock. The design of the regulator includes a differential device that automatically equalizes the warp tension on two beams.

The product regulator is designed to provide a given weft density in raw fabric and to wind the fabric onto a product roller. The required weft density is established by selecting replacement gears of a certain combination. The movement of the fabric is created by the rotation of the felted felt, the surface of which can be covered with a grater, sandpaper or rubber. The worked fabric is removed while the machine is running. The regulator is positive type.

The shed formation mechanism serves to form the shed and ensure the production of tissues of various weaves. The machines can be equipped with eccentric (cam) or carriage shedding mechanisms and jacquard machines. Cam mechanisms are designed for producing fabrics of main and finely patterned weaves with a weft repeat of up to 8 and a number of healds of up to 10. In these mechanisms, the heald frames receive movement from eccentrics of a certain profile placed in an oil bath. When using shedding carriages, the machines can produce fabrics of finely patterned weaves with weft repeat of up to 300 threads and a number of healds of up to 14-18. Jacquard machines are installed when producing large-patterned weave fabrics.

The fold-finding mechanism is designed to disconnect the shedding mechanism from the machine and set the heddles to the fold position, i.e., to the position when the last weft thread is located in the open shed.

Disabling the shedding mechanism can be manual or mechanized.

The batt mechanism serves to beat the weft threads to the edge of the fabric and guide the passage of the weft threads through the shed. The batan beam of rectangular cross-section has a longitudinal hole in which the reeds are attached. A steel comb is attached to the batan beam, which serves as a guide for the passage of the weft inserters. The batan beam is connected with short blades to the batan shaft, the cams of which are placed in an oil bath. The combat (left) box is used to accommodate the following mechanisms involved in laying the weft thread through the shed: combat brake, oil brake (buffer), weft inserter lift, weft inserter spring release, weft returner, weft thread brake and compensator, weft control mechanism, left weft scissors, centering device.

The shuttleless table loom (STB) is designed for the manufacture of products from wool, silk, linen and cotton fabrics. The STB machine is distinguished by high productivity and reliable operation of all components.

Such a device is currently quite widespread.

1 Weaving machine - design and principle of operation

The STB machine works on the principle of laying threads using a special metal layer. The supply of weft yarn to the STB device can reach 2-4 kg. This allows the weaving unit to work for a long time without stopping. A shedding mechanism is installed on STB machines. He can be:

cam;
carriage;
jacquard

The use of a cam mechanism is relevant when producing fabrics with simple weaves; in addition, it is equipped with removable cams with various profiles. Thanks to the variety of cams and the possibility of using ten different heddles, the STB machine can produce large quantities of tissue with various weaving patterns.

This detail also greatly facilitates the process of moving from pattern to pattern and rethreading the device with threads. The capabilities of an STB unit can be most fully realized if it is equipped with a jacquard machine. A do-it-yourself loom, as a technological device, allows you to produce fabric with a coarsely patterned texture.

If you install a multi-color weft device on the STB machine, then not only colored threads can be inserted into the shed, but also threads with different fibrous composition and degree of density. STB machines can be of two types: narrow and wide. Narrow devices have a filling width of 220 cm, and wide ones – more than 250 cm.

On such units it is possible to simultaneously produce several webs. The required width of the fabric being produced is adjusted by moving the receiving box and the middle edge-forming mechanism.

If the STB machine produces webs from several separate beams, its regulator is equipped with an additional differential mechanism. The design of the STB machine allows you to perform several cyclic operations that are connected to each other. This:

shedding;
insertion of the weft into the throat;
surf the weft to the edge of the fabric;
releasing the base to the fabric creation area;
removal of finished fabric from the creation area.

Main The working mechanisms of the STB machine are:

shedding;
mechanisms for inserting the weft into the throat;
beat the weft to the edge of the fabric;
devices for removing and moving the finished web;
mechanisms, release of fabric from the beam.

During the production of fabrics, the base of the machine and the canvas, moving in a longitudinal plane, pass through several guides.

In most modifications, these are rocks, price rods, ropes and chests.

In order to transmit movement to these mechanisms The device is equipped with a drive and a start and stop mechanism. During operation, the drive transmits movement to the central shaft. From the main shaft, the movement spreads to all other moving parts.

In order to avoid defects in the fabric produced, provide greater operational safety and facilitate the operator’s work, the device is equipped with safety, control and automation mechanisms. All these parts are attached to the base, which consists of frames and thread ties.

1.1 How does a loom work? (video)

2 How to make a loom at home with your own hands?

In order to make a loom with your own hands, you must adhere to the following sequence of actions (for example, to assemble you need your own sequence of operations):

A rectangular frame is selected.
Round holes are made in two of its square wooden slats.
At the ends of the slats, round slats with a smaller diameter are inserted into the holes and lined with wedges to avoid backlash.
In the middle part of the side square rail, grooves are made for subsequent installation of the comb.
A plywood bottom is attached to the bottom of the structure to ensure good stability.
The required number of nails in increments of 5 mm is hammered into the first round lath. They will provide tension to the warp thread.
A rear rail is attached, which is used for winding excess fabric.

The comb is made with a height of 15 cm. It can be made from a piece of thick plywood sheet. It is important to remember that the length of the comb must exceed the distance between the side frames. The number of teeth made should be equal to half of the nails driven into the central rail.

The length of the teeth is 7-10 cm, the width is 0.5-0.7 cm, and the gap between them should be 0.5 cm. In addition, a thin nail is hammered onto each individual tooth of the comb. Its length can be 1.7-2 cm. Next, the comb is inserted into round grooves located in the middle part of the machine blade.

You should prepare a wooden plank with a smooth surface in advance.

Its length should be less than the distance between the inside of the machine. Thin nails are also hammered onto the bar in increments of 1-1.5 cm. After this, it is necessary to make a weft, which is a movable transverse part of the weaving device.

The weft can be represented as a device, providing support for the coil, or be separately cut from a plywood sheet as a plank. The thread will subsequently be wound around it. Next, it is necessary to tie pieces of thread equal in length to the nails driven into the front shaft.

The next step is to distribute the threads into even and odd. The even ones are stretched and strengthened on the comb by wrapping them on the nails of the teeth. The odd numbered threads are attached to a movable shaft located behind the comb.

The threads need to be wrapped around the heads of pre-driven nails.

The remaining threads are wound onto the bar while turning it evenly, resulting in the base of the woven fabric. Next, the thread should be wound around the weft, and its end should be secured to the left side of the frame, located in front of the leading front rail. The bar must be raised, and the weft must be pushed into the resulting shed across the threads, moving from left to right.

2.1 Making a mini loom

For small amounts of work, you can make your own simple mini-loom. It is recommended to use a piece of thick cardboard to create the distributing thread of the fork.

Using such a compact device, you can make a small decorative rug without using any special tools.

To do this you will need the following materials and tools:

a sheet of thick cardboard;
yarn;
scissors;
hook;
pencil.

In addition to cardboard, to create a mini-loom, you can use a small sheet of chipboard, plywood or any other dense material that can be cut without difficulty. If in the process of working as consumables If plywood is selected, then holes can be made in it using a regular awl.

In this case, not cuts for threads should be made on the sheet of plywood (as on cardboard), but holes along the edges of the workpiece. To create small decorative items, a cardboard sheet with an aspect ratio of 13x16 cm is suitable. First Markings are applied to the cardboard, along which incisions will subsequently be made.

The future mini-machine is marked in this way: on two opposite sides of a cardboard sheet, marks are made with a pencil in increments of 5-10 mm. In order for the resulting marking to be even, it is necessary to draw parallel lines along the marks that were placed every 5-10 mm.

It is important that the lines run strictly parallel to the unmarked sides of the sheet. After this, following the applied markings, cuts are made on the cardboard sheet taking into account the required depth on two opposite sides. Yarn is taken from which it will form the basis.

Instead of yarn, you can use decorative ribbon or regular thread. Next, the yarn is carefully inserted into the cut of the cardboard sheet, and a small piece of it (2 cm) remains on the wrong side of the improvised cardboard fork.

It should be noted that you need to thread the yarn through the cuts using a “snake”, that is, you need to tie the resulting cutouts on one side of the fork. On the opposite side you also need to create lines of threads.

This side will subsequently be considered the front side. The fabric being manufactured is located on it. It should be remembered that the tension of the threads should be done effortlessly so that the cardboard frame does not bend. For convenience, the working thread can be threaded into a thick needle with a wide eye. The required number of threads is calculated in this way, the outer ones were edge and moved from one row to another.

Combat mechanisms of various designs are used on weaving looms. According to the principle of operation, combat mechanisms can be cam (eccentric), crank, spring, or pneumatic. The most widely used are cam fighting mechanisms. In various designs of these mechanisms, the cam is used as a leading element and as a driven one.

Based on the location of the parts on the machine, the fighting mechanisms are divided into three types: lower combat, middle combat and upper combat.

When producing fabrics on machines with multi-shuttle mechanisms, in some cases it becomes necessary to carry out combat not alternately on each side, but in a more complex sequence. The combat mechanisms of individual designs have devices that can be used to establish a more complex battle sequence. Based on the order of combat, combat mechanisms are divided into sequential combat mechanisms and random combat mechanisms.

Bottom strike mechanism

The fighting mechanism (Fig. 5) of a pile weaving loom belongs to the mechanisms of the lower fighting mechanism. Its peculiarity is that the slide 1 freely placed on the shelves 2 , mounted on a horizontal wooden lever - roller 3 and having a protrusion on the left side. During normal operation of the machine, the combat roller 4 presses the slide 1 to the ledge of the skids 2 and rejects the roller 3 for throwing the shuttle. But during the reverse motion of the machine, while searching, the roller presses on the slide, deflects it away from the protrusion and passes by without pressing the roller, which is why the shuttles remain at rest. The slide is returned to its working position by a spring 5 .

Buffer" href="/text/category/bufer/" rel="bookmark">a folded spiral belt serves as a buffer 10 .

Despite the fact that the mechanism operates on the principle of a lower strike, the presence of a belt clamp imparts smoothness to the beginning of the movement of the shuttles.

The strength of the strike is regulated mainly by changing the length of the clamp 6 , the beginning of the battle - by rearranging the combat roller in the slot of the crank 11 , fixed on the middle shaft 12 . For normal operation of the mechanism, the combat slide must be installed so that the plumb line lowered from the middle shaft towards the baton falls on the center of the slide protrusion. The start of the fight should occur with the knee of the main shaft in the lower position.

Medium strike mechanism

Let's look at the fighting mechanism of the AT-100-5M machine; this is a cam-type fighting mechanism with a medium engagement (Fig. 6).

On the middle shaft 1 fixed fighting fist 2 , to which the combat roller is pressed 3, rotating on an axis attached to a spindle 4. A stirrup is attached to the spindle tide 14, with the eye of which a short clamp is connected 13. One end of a wooden beam is attached to the clamp 12, and its other end is connected to a long clamp 9, put on the driver 8. The clamp is held on the chase by straps 10. Lower

Rice. 6. Mechanism of the middle strike of the AT-100-5M loom

the end of the driver is inserted into the slot of the shoe 11, which ensures the straight movement of the shuttle during its acceleration. A race is attached to the upper end of the chase with a screw. 6. The start of the battle is regulated by turning the combat cam on the shaft. The force of the fight is adjusted in the following ways: by moving the stirrup on the spindle, by moving the bar 10 on the driver, changing the gap between the clamp and the driver. After flying through the throat, the shuttle is slowed down by shuttle box valves and leather loops 7 , available on each side of the machine and connected to the sub-belt 5 .

The beginning of the fight depends on the structure of the tissue produced. At the start of the fight, the knees of the main shaft should not reach the lower position by 10–15°. To get an earlier fight, the combat cam is turned in the direction of rotation of the middle shaft, and to get a late fight, the cam is turned in the opposite direction.

The movement of the race characterizes the force of the fight, which provides the necessary speed of movement of the shuttle through the throat.

The speed must be such that the shuttle has time to fly through the shed before the warp threads begin to interfere with its movement when closing the shed, and in a timely manner fly into the opposite box, press the valve and lift the persistent tongues of the locking mechanism.

It is necessary to set a small firing force on the machine (since in this case the parts of the firing mechanism wear out less and frequent adjustment of the mechanism is not required. If the firing force is excessive, it is necessary to increase the braking of the shuttle in the box, which leads to rapid wear of the shuttle and the links of the fighting mechanism.

Moving race without taking into account the reduced deformation

Where X– vertical deviation of the roller contact center under the action of the cam toe; l1– length of the combat roller lever; l2– lever length; at– idling of the clamp; l 3 – length of the chase from the base of the shoe to the line of the center of the race hole; l 4 – length of the driver from the base of the shoe to the middle of the clamp.

Fist fighting mechanism of arbitrary combat

Let's consider the fighting mechanism of free combat, which is installed on a loom from the Textima company (Fig. 7).

the figured lever sits tightly 5. The figured lever has a pawl 6 and connected by a clamp 7 with a rush 8. The same device is available on the other side of the machine. The combat sectors are hingedly connected by a rod 9 .

If any resistance arises that limits the movement of the chaser, breakdowns of it and other parts of the fighting mechanism are inevitable, therefore the design of the fighting mechanism includes hinged joints. For example, the axis of rotation of the chaser is placed in the wing and is held by a spring connecting it to the axis of the chaser.

Regulation of the beginning and strength of the battle is carried out in the same way in the combat mechanism of the middle battle.

Cam fighting mechanisms are distinguished by their robust design and the ability to create enough great strength battle. The free-range combat mechanism is installed on multi-shuttle looms. Here, arbitrary movement of the shuttles is carried out, i.e., the laying of weft threads of different colors or qualities by several shuttles with an even or odd number of insertions. In this case, the shuttles can be thrown not only alternately from the right and left shuttle boxes, but also several times in a row from the shuttle box on one side of the machine. When using such mechanisms, you can achieve almost any color maneuver of the weft threads in the fabric.

1.4.2. Shuttleless weaving looms

laying the weft thread into the shed

Weft insertion with small-sized micro-inserters

The principle of laying the weft thread on STB-type looms differs from the principle of laying the weft on shuttle looms. On STB-type looms, several mechanisms are involved in weft insertion, which can be divided into two groups depending on their location.

The following mechanisms are located in the weft fighting box: in its rear compartment there is a fighting mechanism, a weft inserter lift, a weft inserter spring release, a weft return spring release; in the upper front compartment there is a mechanism for transmitting movement to the returner, left scissors and a centering device, and a left weft controller.

In the receiving box there are mechanisms for braking the weft inserters, returning the weft inserters, a spring release for the weft inserters, a right weft controller, a controller for landing the weft inserters, and a stacker for placing the weft inserters on the conveyor. The mechanisms involved in laying the weft also include an oil spray pump; return conveyor for weft inserters; bobbin holder, brake and weft thread compensator; weft color changing mechanism; weft thread accumulator (on those machines where this is necessary).

Weft laying pattern. On weaving machines of the STB type, the weft thread is laid by small-sized inserters from stationary cross-winding bobbins located on the left side of the machine. Weft spacers (Fig. 8) are a steel plate with a gripper for the weft thread. The body of the weft layer is hollow, having the cross-sectional shape of an unequal octagonal prism. The cone-shaped toe of the layer improves the flight conditions of the layer along the guide comb. A steel spring is fixed inside the body using rivets, ending at the rear with jaws for capturing and holding the weft thread. To open the spring jaws, a weft return spring and a spring opener tooth enter into the hole of the inserter, when it is in the fighting box, to transfer the thread to the inserter. In the receiving box, the tooth opens the spring to release the thread and transfer it to the thread catcher.

Rice. 8. View of the weft inserter of the STB type loom

Laying the weft on machines with small-sized inserters is carried out as follows (Fig. 9). Weft thread from bobbin 1 passes through the peephole 2 , thread storage 3, eye 4, weft brake 5, guide eye 6, compensator eye 7, guide eye 8 and is held by the jaws of the weft returner 9. After transferring the weft thread from the returner to the weft inserter 10 it is laid in the throat. Centering device 11 positions the weft thread centrally in relation to the weft returner. Catchers (clamps) 12 approach the edges of each fabric and pinch the ends of the weft emerging from the edges. Scissors 13 used for cutting thread. Sometimes an additional tension device is installed between the bobbin and the thread collector.

Rice. 9. Layout of weft on the STB machine

The insertion of weft threads into the shed is carried out by a small-sized weft inserter of the following dimensions: length 90 mm, width – 14 mm, height – 6 mm and weight – 40 g.

Inside the body with rivets 7 flat spring attached 2, ending with grips 5 in the form of two sponges.

To open the spring grips at a certain moment (according to the cyclic diagram), there is a cutout in the weft inserter body 4, which includes the spring opener, the weft spacers of the receiving box, and the hole 3, which includes the spring opener for the weft fighting box spacers.

The compression force of the jaws of the grippers of the inserters depends on the type and linear density of the processed yarn.

Laying conditions. The combat mechanism of STB-type looms, in design and the material from which it is made, differs significantly from the combat mechanisms of shuttle looms. The acceleration of the weft-laying shuttle is carried out due to the elastic moment of the twisted torsion shaft. The magnitude of the twist angle of this shaft determines the strength of the fight. The combat mechanism parts are made of alloy steel, which ensures its durable and precise operation.

The fighting cams on narrow and wide STB type machines are the same. The increase in the duration of the weft inserter's flight on wide machines by 400 is explained by the filling width of the machine and is ensured by a shift in the start of the fight. The speed of movement of the weft inserter shuttle on narrow and wide machines is approximately the same.

The operating periods of the combat mechanisms of STB type looms are given in Table. 2.

table 2

Twisting of the torsion shaft, degrees

The start of the battle

layer

to the reception

box, no later, hail

layer

duck through the throat,

The speed required for the shuttle to fly through the throat is provided by a combat mechanism, the operation of which is based on the use of the potential energy of a twisted roller. The design of the fighting mechanism of the Sulzer machine is no different from the design of the fighting mechanism of the STB type loom.

The torsion roller, depending on the angle of twist and its elastic properties, through the corresponding levers, communicates movement to the weft inserter, the equation of motion of which can be represented with a sufficient degree of approximation in the form

Where v1– initial speed of the weft layer during free flight, m/s; v2– final speed of the weft layer during free flight, m/s; Fy– tension of the laid weft thread, N; T– reduced friction force of the weft inserter on the guide teeth of the channel, N; Q– the force of drag of air during the movement of the weft inserter in the throat, N.

Assuming the movement of the layer to be uniformly slow, and the acting forces in the process of laying the weft constant, we obtain:

The fighting mechanism gives the plotter a weft maximum speed when flying in the throat. This speed during laying is reduced due to the action of the above forces.

The force of air drag can be determined by the formula

Where W – air drag coefficient; S – frontal area of the weft layer, m2; vср – average speed of the duck layer in free flight, m/s; R - air density, kg/m3.

Calculations show that the force of air resistance is several centinewtons.

During the period of movement through the shed, the weft inserter experiences friction against the guide teeth. The reduced friction force of the layer can be determined by the formula

Where fpr– reduced coefficient of friction of the weft inserter on the guide teeth of the channel; G – weight of the weft inserter, kg; R - normal component of the inertia force of the weft inserter, N.

Calculations show that this force is also small, so the deceleration of the layer in the shed is most affected by the tension of the weft.

Weft thread tension on a STB type loom

The weft thread on a weaving loom of the STB type is subjected to various loads that vary in magnitude, direction and time of exposure. The total tensile force is multifactorially dependent on the kinematic parameters of the thread movement, its length, transverse geometric dimensions, composition and structure, pre-tension on the package, wrap angle of the guide elements, sliding friction coefficient between the thread and thread guides, etc.

The weft tension curve is shown in Fig. eleven.

The tension curve is characterized by the presence of six characteristic sections:

1 – begins from the moment the weft inserter accelerates (approximately 105°), ends after the inserter reaches maximum speed and, flying in the shed, completely takes out the “slack” of the weft thread;

2 – begins from the moment the thread begins to unwind from the bobbin and continues until the moment the weft starts to be braked by the foot of the weft brake mechanism;

3 – corresponds to the period of action of the weft brake during laying of the weft and continues until the moment the layer flies into the receiving box;

4 – corresponds to the process of braking the layer in the receiving box and continues until the start of the return of the layer;

5 – characterized by the presence of a section of constant tension, which continues until the centered weft thread is captured by the return jaws;

6 – continues until the end of the thread is retracted by the weft returner to its original position to transfer it to the inserter.

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Rice. 11. Weft tension curve on a STB type loom

As it moves into the shed, the weft thread bends around a number of guide eyes, resulting in its tension Fn increases at the traveling end. This tension can be determined by the formula:

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The weft tension at the trailing end of the thread is created by the winding resistance.

As the thread is unwinding from the package, a rotating balloon of thread is formed around the package. To estimate the maximum thread tension in the balloon Fb, which occurs at the top of the balloon, we use the formula:

Where F1 – thread tension at the point of separation from the bobbin, N; https://pandia.ru/text/78/648/images/image036_14.gif" width="96" height="37"> – angular velocity of rotation of the cylinder;

Where γ – angle of the thread element from the package generatrix, rad; ν – axial speed of thread winding, m/s; Rb – radius of the bobbin at the point of separation of the thread from it, m.

The formula was derived under the condition that the axial speed of unwinding the thread from a stationary package is constant.

Where Fo – thread tension in the area of initial equilibrium of the thread on the package, N; f´– maximum coefficient of adhesion friction of the thread on the package; ψ´ – angle of grip of the movable section of the thread on the package, rad.

The free-winding tension is maintained in the thread until the brake foot acts on it, which presses the weft against a flexible spring-loaded plate.

The average tension of the weft thread during the period of action of the weft brake is

where F T– friction force in the weft brake, N .

The friction force in the weft brake depends on the magnitude of the friction coefficients on the surface of the plate f1, paws f2 and normal pressure forces N plates on the thread (Fig. 12)

Spring preload force

Where z– spring stiffness coefficient of the weft brake (24 cN/mm); λ0 – the amount of spring pre-tension, m; λ1 = 2∆l1/L– deformation of the spring during the period of action of the weft brake, m.

In Fig. Figure 13 shows an oscillogram of weft tension on a weaving machine of the STB type when producing fabric with an average weft density.

Period III corresponds to the time of action of the weft brake during the flight of the layer in the throat.

Period IV corresponds to the braking of the layer in the receiving box, while the weft returner begins to move in the opposite direction.

Period V corresponds to the action of the brake and compensator, while the tension reaches a certain value, which is necessary for the formation of tissue.

Period VI begins at the moment when the centered weft thread is captured by the weft return jaws; During this period, the end of the wedge is retracted by the returner to its original position to be transferred to the layer.

On weaving machines of the STB type, weft compensators are installed, which pull out the excess length of the thread from the shed and release the missing length into the shed during the laying process. These devices are necessary to maintain constant thread laying conditions. The operation of the compensator largely determines the nature of the change in the tension of the weft when it is laid in the shed. The main quantities that determine the geometric and kinematic characteristics of the compensator are the relative movement S0 and relative speed v0 weft thread (relative to the movement and speed of the compensator).

Where Sн And vн– displacement, m, and speed of the weft thread, m/s, equal to the displacement and speed of the layer, respectively; SГ And vG– movement and speed of the weft thread when approaching the eye of the compensator.

For optimal operation of the compensator, it is necessary that its angular velocity and relative displacement tend to zero.

Combat mechanism of a weaving loom type STB

Let's consider the operation of devices that ensure weft insertion on shuttleless machines. When laying weft, it is customary to distinguish ten periods (Fig. 14).

Period I. The inserter with the clamps open is directed towards the weft returner, which holds the tip of the thread. The brake clamps the thread, and the compensator is in the upper position.

Period II. The layer enters the line of flight and combat, its clamps are open and located behind the clamps of the weft returner, which is still holding the thread.

Period III. The weft returner clamps are opened and the inserter clamps are closed, the thread is transferred to the inserter, who is prepared for flight. The canard brake begins to open, the compensator begins to lower.

Rice. 14. The main periods of laying weft thread on an STB type loom

Period IV. A fight occurs, as a result of which the layer, with the clamped weft thread unwinding from the bobbin, flies through the shed into the receiving box. The canard brake is fully open and the compensator is lowered.

Period V. To reduce the tip of the weft thread protruding beyond the edge of the fabric on the right, the inserter moves slightly back to the right edge of the fabric. The weft brake closes and the compensator rises and removes from the shed the excess length of thread created when the inserter returns to the edge. The weft returner has approached the edge of the fabric, its clamps begin to close.

Period VI. The centering device, located near the left edge, approaches the weft thread and positions it in the center of the weft return clamps, which then close and capture the thread. Thread holders approach the edges of each fabric and clamp the ends of the weft protruding from the edge.

Period VII. The opened scissors approach the weft thread, the inserter located in the receiving box opens the clamps and releases the thread.

Period VIII. The weft thread is cut with scissors near the warping box and between the webs. The lift lifts the next layer and moves it to the fighting box, the layer in the receiving box begins to move towards the conveyor.

Period IX. The weft returner moves to the left, the compensator rises and selects excess thread, the reed and thread holders move to the edge of the fabric, the weft thread is nailed to the edge of the fabric; By this time, the scissors have returned to their original position.

Period X. The weft returner moves to the extreme left position, the compensator finishes picking the thread and comes to the extreme upper position. The ends of the weft thread pass from the thread holders to the needles of the edge formers and are inserted into the shed. Taking into account ten periods, these devices are adjusted. Moreover, when producing a different range of fabrics, the adjustment will be different.

The fighting mechanism of the STB type loom is designed to ensure that the weft inserter is inserted through the shed to the entire filling width of the loom. The direction of movement of the weft inserters during the acceleration period is determined by the guide of the weft fighting box and the channel of the guide comb of the baton. The initial speed of the weft inserters does not depend on the speed of the machine and is determined by the potential energy of the twisted torsion shaft.

The combat mechanism has the following device (Fig. 15, a). On the cross shaft 2 a combat cam is rigidly attached to the three-slot eccentric with two bolts 1 , which together with the shaft rotates clockwise. On a fixed axis 19 Three-arm lever swings freely 18 , consisting of two parallel plates connected to each other.

Between these plates on the axis 21 the roller rotates 20, which is in contact with the cam 1 . Upper arm of three-arm lever 18 through the hinge link 17 connected to lugs 16 hollow shaft 15. At the end of this shaft there are clamping bolts 3 the chaser is fixed 4. The upper end of the chaser with an earring 5 connected to race 7 , which moves along the guide of the duck-fighting box and the ledge 8 throws the duck layer 6 through the throat

Inside the hollow shaft 15 placed torsion shaft 14, one end of which is connected by splines to the splines of the hollow shaft, and the other is also connected by splines to the winding clutch 10, attached to the casing 13 bolt 11. The casing is attached to the duck fighting box with three bolts 29 (Fig. 15,b).

A pressure bolt is screwed into the housing boss 12 (see Fig. 15, a), which, when wrapped, can put pressure on the finger 9, fixed in coupling 10. On another casing tide 13 two bolts 31 (see Fig. 15, b) the scale is fixed 30 with graduation from 00 to 32°.

Rice. 15. Combat mechanism

There is a mark on the winding clutch, by which you can determine the position of the clutch relative to the casing (relative to the twisting of the torsion shaft).

The combat mechanism system also includes a shock-absorbing device in the form of an oil brake, which consists of a connecting rod 26 (see Fig. 15, A), hinged to the lower arm of a three-arm lever 18, piston 25, cylinder 22, oil drain channels and adjusting bolt (needle) 23. All oil brake parts are located in the housing 24, which is attached to the body of the combat box with six bolts.

The purpose of the oil brake is to absorb the kinetic energy of the moving parts of the combat mechanism after the canard inserter is separated from the race.

When the cross shaft rotates 2 clockwise cam 1 presses on the roller 20 three-arm lever 18 and turns it around. Upper end of three-arm lever 18 presses on the hinge link 17, and the last one - on the eyes 16 hollow shaft 15, turning it. Hollow shaft 15, rigidly connected through the splines to the torsion shaft, it will twist it, which is why elastic forces arise in the latter, since the other end of the torsion shaft is fixedly fixed in the winding clutch 10. Chase 4, rotating together with the hollow shaft counterclockwise, it takes races 7 to the rear, starting position for combat . Rotating the three-arm lever 18 and the twisting of the torsion shaft will continue until the axes of the lever, the hinge link and the eyes of the hollow shaft go beyond the dead position, and the roller axis 20 will not deviate from this position by 0.1–0.2 mm.

With further rotation of the cam 1 trigger rollers 28, located on both sides will touch the middle arm of the lever 18 and put pressure on him. As a result of this, the lever will rotate counterclockwise and, as soon as it passes the dead position, the torsion shaft will begin to unwind. As a result, the hollow shaft 15 will turn clockwise along with the chaser, and race 7 with its protrusion 8 the weft inserter will throw it through the gap. After the fight, the torsion shaft unwinds completely.

Braking of the combat mechanism components during combat is carried out as follows.

When the upper arm of the three-arm lever is turned counterclockwise, its lower arm moves clockwise, forcing the piston 25 enter the cylinder 22. During this movement, the piston will brake sharply, as oil will begin to exit the cylinder through the annular gap between the piston and the cylinder and through the annular gap in the adjusting needle. The gap between the piston and the cylinder remains constant during operation, since it is determined by the design dimensions of these parts, and the gap in the adjusting needle can change.

To produce fabrics with weft threads of different colors, fibrous composition or structure, multi-shuttle looms are used. For each type of weft, the machine has separate shuttles, which are put into operation in a certain sequence.

Of the shuttleless looms, the most widely used in the USSR are LTPR pneumatic looms and STB looms with small-sized inserters.
On ATPR machines, weft thread is laid using rapiers, which are coaxially located cylindrical tubes (outer and inner), rigidly connected to nozzles. Compressed air is supplied to the channel of the right rapier, and it is sucked out from the channel of the left rapier. The thread from the right rapier is transferred to the left, receiving one. When transported through the shed, the thread does not have a rigid connection with the rapiers. After the rapier leaves the shed, the weft thread remains in it, is cut off with scissors at the right edge and nailed with a reed to the edge of the fabric.
Pneumatic machines practically produce the entire mass range of cotton, viscose and cotton fabrics of plain, twill and satin weaves. The productivity of LTPR machines is 1.5-2 times higher than the productivity of automatic weaving machines. They operate almost silently, which distinguishes them favorably from shuttle machines.
Shuttleless pneumatic looms are much less common, in which the weft thread from a stationary conical bobbin is directed into a nozzle and laid through the shed with periodically supplied compressed air. Even less commonly used are hydraulic machines in which the weft thread is thrown through the shed with a jet of water supplied under pressure.
On a pair of rapier looms, the weft is inserted through the shed using rigid or flexible rapiers moving towards each other. One rapier, carrying a drink, passes it in the middle of the throat to another, counter, pulling the thread through the second half of the throat.
On STB machines, where the principle of fabric formation by shuttle machines is preserved, the weft is inserted into the shed by small-sized inserters - micro-shuttles. The spacer, which is a small metal plate, grabs the end of the PTP from a stationary conical reel and pulls it through the open mouth.
In the opposite direction, the spacers without thread are moved under the warp threads by a transport mite, which transfers them to the opposite side of the machine, again into the fighting box. There are 13-17 layers at work at the same time. The duck inserted into the throat is trimmed, and its end is inserted with an edge former into the next throat (laying edge).
STB machines can work with eccentric (cam) shedding mechanisms, with carriages and jacquard machines. STB machines are produced with filling widths from 175 to 330 cm. Edge-forming machines can be installed on them to produce three blades at the same time. STB machines, which have become widespread, produce high-quality fabrics from all types of raw materials, including wool in large quantities. The productivity of STB machines is 2-2.5 times greater than that of shuttle machines.
Multi-threaded weaving looms currently have limited use, but are promising. Multi-link machines with a wavy throat are characterized by: that along the entire filling width of the machine, each heald is divided into a certain number of small groups of heald sections, the width of which depends on the weave pattern. Each section is driven by an individual shedding cam.

Educational institution

Course project on PTM

Executor:

student group 4 Tk-33

Novikova V.M.

Project Manager:

Assoc. Belov A.A.

Vitebsk, 2011.

Ministry of Education of the Republic of Belarus

Educational institution

"Vitebsk State Technological University"

Department of Light Industry Machines and Apparatuses

Settlement and explanatory note on PTM

Topic: “Design of the regulator mechanism of the STB base”

Executor:

student group 4 Tk-33

Novikova V.M.

Project Manager:

Assoc. Belov A.A.

Vitebsk, 2011.

Introduction………………………………………………………3

General characteristics of the machine………………………………4

Technological diagram of the machine..…………………………. .....6

Technical characteristics of the machine…………………………7

Description of the machine operation according to the kinematic diagram………...8

Kinematic calculation…………………………………….....9

Description of the operation of the designed mechanism.……………..9

Necessary calculations…………. …………………………...eleven

8.1. Calculation of rotation speeds of the working parts of the machine..…….11

8.2. Calculation of rotation speeds of the working parts of the machine:…12

8.3. Weft density calculation. ………………………………12

8.4. Determination of filling tension………………..13

8.5. Beam calculation……. …………………………………….....15

General conclusions and suggestions……………………….....16

Specification ……………………………………………. ..18

Literature

Introduction

Fabric making is one of the labor processes that were learned by man at the very first stages of the development of material culture. Weaving arose earlier than spinning (the first mention of weaving was 30-20 thousand years BC) - the first fabrics were made from leather, bast, and twigs.

The first fiber used in weaving was nettle. Cotton fiber was used in India 3-2 centuries. BC, linen - Roman Empire 2-1 BC; wool weaving - in the 9th century. AD Europe and Asia. China is considered the birthplace of silk.

The first frame looms were horizontal and vertical. Among vertical people, people worked standing up, and from the word “stan” (to stand) the word machine for weaving appeared. Weaving was considered a gift from the gods. Until now, the art of ancient weavers is unsurpassed, because... in the English museum, the mummy has a woven tape on her forehead with a thread density of warp = 213 n/cm and a weft thread density of 83 n/cm. Modern weaving looms reach a maximum warp density of up to 150 n/cm. And in 1733 Englishman John Kay invented the shuttle airplane. The creation of the shuttle caused the need to create a spinning machine, because... weavers did not have enough yarn for fabric. In 1765 The Englishman James Havrivs invented a spinning machine with 4 spins and named it in honor of his daughter “Jenny” (the word “engineer” comes from the adjusters of these machines). After the invention of the spinning machine, there was a need to create a mechanical loom, and it was invented by Edmund Cartwright in 1786. In 1894 The Englishman James Northrop invented an automatic bobbin changer and after that weaving machines began to be called automatic. In Russia, shuttles appeared in 1814, and mechanical ones. machines in 1836 And their mechanic Nesterov suggested using them for wool weaving.

The first shuttleless weaving machine was patented in 1841 by John Smith. However, it took many millennia for humanity to move from primitive hand-weaving fabrics to modern mass production of fabrics of various structures from a wide variety of raw materials in powerful factories equipped with automatic machines. Over the past 20-25 years, significant changes have occurred in the design of shopping malls. machine

The following machines are produced: for the production of cotton, wool, silk and linen fabrics, fabrics from glass threads and metal mesh; for the production of light, medium and heavy fabrics; narrow and wide; single-shuttle and multi-shuttle; cam, carriage and jacquard.

Machines of the STB type with a small shuttle-laying machine are successfully used for the production of fabrics both from fine chemical threads and from wool and cotton yarn of various linear densities. These machines can produce narrow fabrics in several webs across the width of the machine and wide fabrics in one or two webs.

General characteristics of the machine

STB weaving machines are designed for the production of wool, silk, cotton and linen fabrics, as well as fabrics made from mixed fibers. The high productivity of the machine and the reliable operation of its components and mechanisms have ensured its widespread use. This is greatly facilitated by the use in these machines of the principle of laying the weft thread using a special metal layer.

Feeding the machine with weft yarn from stationary packages, the weight of which can reach several kilograms, allows the machine to work for a long time without stopping. This reduces the weaver’s workload and contributes to the production of high-quality fabrics.

On STB machines, a shedding mechanism of one of three types is installed: cam, carriage or jacquard machine. The cam shedding mechanism is used in the production of fabrics of simple weaves. It is equipped with removable cams of various profiles. The variety of cams and the possibility of using up to ten healds in a thread make it possible to produce fabrics with various patterns, with a weave repeat of up to 8. Installing a high-speed carriage on the machine for 14 or 18 healds significantly expands the assortment capabilities of the machine. In this case, it is possible to produce fabrics with more complex weaves. In addition, the transition from pattern to pattern or refilling of the machine is greatly facilitated, which cannot be said about the cam shedding mechanism

The capabilities of the machine are most fully used if it is equipped with a jacquard machine. Using the machine, you can produce large-patterned fabrics. In addition, installing multi-color weft devices on the machine allows you to introduce not only colored threads into the shed, but also threads of different fibrous compositions or different linear densities.

STB machines are divided into: narrow and wide. Narrow machines include those whose filling width does not exceed 220 cm, and wide ones - 250 cm or more. Depending on the filling width of the machine, it can produce one or more webs. The required web width is achieved by shifting the right receiving box and the middle edge-forming mechanisms, as well as replacing the connecting shafts. If the production of webs occurs from separate beams, the main regulator of the machine is equipped with a differential mechanism.

On STB machines it is possible to process the following types of weft threads: woolen, half-woolen, from a mixture of wool with other fibers 200-15.6 tex; cotton threads and a mixture of cotton with other fibers 83.3 - 5.9 tex; chemical complex threads and natural silk threads 100 - 2.2 tex; linen threads 69-16.7 tex.

In accordance with GOST 12167-82, STB weaving machines are divided into seven groups.

The first group includes machines with a filling width along the reed of 180 cm, the second - 220, the third - 250. The fourth, fifth, sixth and seventh groups combine machines with a filling width of 280, 330, 360 and 400 cm. It is allowed to manufacture machines with a filling width of 280, 330, 360 and 400 cm. fillings 175, 216 and 390 cm. Each group consists of four types of looms: without a weft change mechanism and equipped with two-, four- or six-color mechanisms. For example, the STB2-180 machine belongs to the first group. It is equipped with a two-color weft changing mechanism and its reed filling width is 180 cm.

The process of fabric formation on a weaving loom consists of the following basic technological operations cyclically interconnected with each other:

1) shedding;

2) introducing the weft into the throat;

4) releasing the base into the tissue formation zone;

5) removal of accumulated fabric from the formation zone.

The main working mechanisms of the weaving machine:

1) shedding;

2) introducing the weft into the throat;

3) beat the weft to the edge of the fabric;

4) removing the accumulated fabric from the formation zone and moving the base in the longitudinal direction;

5) releasing the warp from the beam, creating tension.

When moving longitudinally, the base and fabric pass through a number of guide bodies (rock, sometimes price rods, ropes, chest).

To transmit movement to the mechanisms, the weaving machine has a drive and a start and stop mechanism. The drive communicates movement to the main shaft of the machine, from which all mechanisms receive movement.

To prevent the formation of fabric defects, ensure work safety and facilitate the work of weavers, a number of safety, control and automation mechanisms are installed on the loom. All mechanisms of the loom are mounted on a frame consisting of frames and links.

Tissue formation on automatic machines STB is similar to its formation on shuttle looms: the usual order of operations in the fabric formation process is maintained (opening the shed, laying one weft thread, closing the shed, bringing the weft thread to the edge of the fabric, opening the shed again, etc.)

In the preparatory department of weaving production, a certain number of warp threads of the required length are wound onto the beam (according to technical calculations for a given type of fabric).

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