DETERMINATION OF THE FRICTION FORCE BETWEEN THE ROLLER OF THE POLYMER COMPOSITION COATING EQUIPMENT ON THE SEAMS OF TARPAULIN MATERIALS AND THE SURFACE OF THE TARPAULIN

ABSTRACT

The article describes the features of the device for applying a polymer coating in lines and drying them in tarpaulin materials. A formula has been obtained for determining the friction force between tarpaulin materials and the surfaces of the main working bodies of the rollers that apply the polymer during their interactions, the recommended values of the parameters of the rollers have been determined.

АННОТАЦИЯ

В статье описаны особенности устройства для нанесения полимерного покрытия на линии и их сушки в брезентовых материалах. Получена формула для определения силы трения между брезентовыми материалами и поверхностями основных рабочих органов роликов, наносящих полимер, при их взаимодействии, определены рекомендуемые значения параметров роликов.

Keywords: Sewing machine, device, roller, polymer composition, vibration, rigidity

Ключевые слова: швейная машина, устройство, валик, полимерная композиция, вибрация, жесткость.

1. Introduction

The existing sewing machine has a design mounted on the needle holder mechanism and designed to soak the polymer composition. This design moves in complete harmony with the other organs of the sewing machine. The machine does not have a needle, thread adjuster, needle thread guide, etc [1].

Additional nodes are the vessel, which is attached to the head of the sewing machine and tightly closed with a stopper, and the pipes, which supply the liquid phase polymer composition. The device for processing shears of textile materials consists of a holder (with which the device is fastened to the needle holder of a universal sewing machine), a control block and a toothed rail. Between the gear rail and the needle holder is a dosing tube and a means of delivering a liquid phase polymer in the form of a conical-tipped and cross-cut piston.

In another device, the system that delivers the liquid phase polymer includes a node for applying the polymer to the edges of the garment details, and supports for placing the item on the gear rail when pushing it. The liquid phase polymer is applied to the part shears by means of rotating rollers located opposite the contact method. The frame of one of the rollers has a special geometric shape, while the other is covered with a porous material (foamed polyurethane coating) and coated with a polymer composition [2].

Both designs not only prevent fabric cuts from being soldered during the entire period of operation of the product, but also stabilize the cut shapes and lead to yarn savings. But their effectiveness is low.

It is recommended to improve the structure and dry the polymer coating immediately after application [3].

2. Materials and methods

The essence of the existing device for applying the polymer composition to the seams of the attached parts is to reduce the slippage of material threads along the seams by strengthening the structure of the fabric using the polymer composition, to reduce the complexity of the process and multi-stage processing. The rotation is carried out by contacting the details of the product with rollers impregnated with the composition. The device consists of a sewing machine body, a soaking bath, reciprocating rollers covered with porous material. The rollers are located on both sides of the attached parts and rotate by touching the material directly. The soaking tub is divided into two homogeneous parts, in which the upper bath is connected to the lower roller located on the working platform of the machine and the glue delivery adjuster with the upper roller through the supply pipe. The bottom roller is partially immersed in the bottom tub. The rotating rollers are connected to each other by means of a belt extension. The rotational movements of the rollers occur due to the frictional force with the materials being attached. In this case, the upper roller applies the polymer composition to the upper layer of the fabric, and the lower roller to the lower layer of the fabric. The polymer composition lubrication device is mounted behind the reaction and gear rail of the sewing machine. Electric heating coils are installed on both sides of the fabric to quickly dry the adhesive composite applied to the seams of the attached materials. The housings are attached to the car body along with the fabric guide elements. The temperature inside the enclosures is controlled using a current regulator.

2.1. Determination of the friction force between the polymer coating roller and the tarpaulin on the tarpaulin seams.

The frictional force between the polymer coating roller rubber bushing and the tarpaulin seam surface is mainly the spring compression force, the roller weight force, and the centrifugal force generated by the roller rotation to a certain extent. It should be noted that the effect of friction on the polymer coating is significant. But since the polymer is a directly coated zone, its effect will not be sufficient. The compressive strength of the spring, as well as the tightness of the rubber bushing play an important role. The contact surface of the rubber bush increases from deformation. It is important that the rotating roller and tarpaulin sliding speeds are compatible.

When the roller interacts with the tarpaulin seam surface, the following forces are generated: gravitational force, centrifugal force, spring compressive force, frictional force, reaction force.

The calculation scheme is shown in Figure 1. We define the forces acting:

Figure 1. Calculation scheme of the zone of influence of the polymer coating roller and material on the seams

Gravity:

                                      (1)

Centrifugal force [4,5]:

                        (2)

here 𝜔_r- roller angle speed.

External compression spring and rubber bushing virginity:

                                              (3)

here, α- roller rubber bushing deformation zone coverage angle, R- roller radius.

Friction force [6,7]:

                                                        (4)

here, - coefficient of friction between the roller surface and the tarpaulin material; N- generalized compressive strength.

It should be noted that there is a layer of polymer composite between the roller surface and the tarpaulin material. In this case, the coefficient of friction between the roller bushing and the surface of the tarpaulin was determined experimentally. The calculations use the ratio of the coefficient of friction of the roller surface and the linear velocities of the tarpaulin surface [8]. In this case, if the velocities are equal, there is no slip, ie the coefficient of friction has a maximum value, in which case;

                                                     (5)

The closing surface of the roller bushing and tarpaulin surfaces leads to a change in the frictional force, as well as a change in the value of deformation of the flexible bushing, which determines the calculated surface area:

                                           (6)

 (7)

here 𝜔_р- roller angular velocity, a-roller rubber bushing deformation zone coverage angle, R-roller radius, - coefficient of friction between the roller surface and the tarpaulin material; N- generalized compressive strength, l_р- the width of the roller.

It should be noted that the vertical vibrations of the roller, the elasticity of the tarpaulin material, the forces of inertia, their relative smallness were not taken into account when determining the friction force

3. Analysis and duscussion

3.1. Numerical solution of the problem and analysis of results.

According to the analysis of the obtained graphs, the coefficient of virginity of the spring and roller bushing is given. when a = 0,5 is rejected С_l=(0,25ч1,8)·10³ N/m it can be observed that the friction force increases in a nonlinear pattern from 5,0 N to 16,1 N when it varies in the range. (Figure 2, Figure 1). It can be noted that the friction force increases from 1,.41 N to 5,1 N when the deformation coverage angle decreases to 0.2 rad. Hence the recommended coverage angle α=(0,32ч0,36) taking into account the rejection, the coefficient of virginity quoted to ensure that the friction force is sufficient (1,4ч1,6)·10³ N/m it is recommended to take in the range.

1-α=0,5 rad;  2-α=0,4 rad;  3-α=0,3 rad;  4-α=0,2 rad.

Figure 2. Changes in the friction force between the roller and the surface of the brezent graphs the dependence of the coefficient of friction between the roller and the quoted coefficient of friction of the roller

It is known that when the linear velocities of the tarpaulin material on the roller surface are equal to each other, the polymer coating is applied evenly, ensuring high strength. If this speed difference increases, the polymer consumption decreases and the friction force between the roller and the tarpaulin decreases. Hence, as the force f₁ increases, the friction force also increases (Figure 3, Figures 1-4). In particular, when the polymer mass is 0,6 · 10^-2 kg and the deformation depth is 1.5 · 10^-3 m, the friction force between the roller and the tarpaulin increases from 0.8 N to 8.1 N when the values of f1 increase from 0.04 to 0.32. increased in linear regularity. However, we can see that the F_fric values increase from 2,32 N to 17,2 N when the mass of the coating polymer is 2,4 · 10^-2 kg and the deformation depth is 4.5 · 10-3 m and f1 increases to 0.32 (3 -picture, 4-graph). To ensure that the polymer coating is applied evenly to the tarpaulin seams and that the friction force is greater than Ffric≥ (12 ч 18) N, it is recommended to reduce the difference between the roller and tarpaulin linear velocities and obtain f₁ values in the range (0,25 ч 0,35).

1-m_pol=0,6·10^-2kg;  Δ=1,5·10^-3m;    2-m_pol=1,2·10^-2kg;  Δ=2,5·10^-3m;

3-m_pol=1,8·10^-2kg;  Δ=3,5·10^-3m;    4-m_pol=2,4·10^-2kg;  Δ=4,5·10^-3m.

Figure 3. Graphs of the change in the frictional force between the roller of the equipment covering the polymer composition of the tarpaulin seam and the surface of the tarpaulin material and the change in the ratio of the linear velocities of the tarpaulin

Also, on the basis of the research, graphs of the change in the frictional force between the roller of the equipment coating the polymer composition and the surface of the tarpaulin material on the tarpaulin seams were changed, which are shown in Figure 4.

It is known that the greater the total mass of the roller, the greater the friction force. According to the analysis of graphs, when R=1,2·10^-2 m, my values increase from 4,0·10^-2 kg to 12,3·10^-2 kg, if the friction force increases in a nonlinear pattern from 0.92 N to 5.35 N. F_fric values were found to increase from 7.1 N to 18.8 N when R = 2.4 · 10^–2 m. Hence, it is recommended to make the roller radius and mass larger, i.e. R = (1,6 ч 1,8)·10^-2 m, m_y = (8,0 ч 10)·10^-2 kg, to ensure high friction force.

1-R=1,2·10^-2 m;   2-R=1,6·10^-2 m;   3-R=2,0·10^-2 m;   4-R=2,4·10^-2 m.

Figure 4. Graphs of the dependence of the change in frictional force between the roller of the equipment covering the polymer composition on the tarpaulin seams and the surface of the tarpaulin material with the change in the applied mass of the roller

4. Conclusions. A mathematical model representing the oscillations of the polymer composition coating equipment on the tarpaulin seams on the composite roller axis was obtained, the laws of vibration of the roller axis on the basis of analytical and numerical solutions were obtained.

The formula for calculating the friction force between the polymer coating roller and the tarpaulin on the tarpaulin seams was determined taking into account the total mass of the roller, inertia and geometric dimensions, the inertia of the flexible elements, the ratio of the roller and tarpaulin linear velocities. The recommended values of the roller parameters are defined.

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