SAW CYLINDER DESIGN WITH SHAFT WITH LONGITUDINAL SLOTTED GROOVES

ABSTRACT

The article proposes an efficient, resource-saving design of an elastic bearing support for sawmills. Expressions are obtained for calculating the amplitude and frequency of vibrations of the saw cylinder on an elastic bearing support. The method of calculating the bending vibrations of the saw cylinder is given. The problem of the dynamics of the machine unit of a two-mass gin-pilocylinder system has been solved. The analytical method provides formulas for determining the laws of motion of the engine rotor and the saw cylinder shaft. According to the results of the experiments, the dependence of the change in the amplitude of vibrations of the saw cylinder shaft on elastic bearings was obtained, and the parameters of the system were justified.    

АННОТАЦИЯ

В статье предложена эффективная, ресурсосберегающая конструкция упругой несущей опоры лесопильных заводов. Получены выражения для расчета амплитуды и частоты колебаний цилиндра пилы на упругой подшипниковой опоре. Приведена методика расчета изгибных колебаний цилиндра пилы. Решена задача о динамике машинного агрегата двухмассовой джин-пилоцилиндровой системы. Аналитический метод дает формулы для определения законов движения ротора двигателя и вала цилиндра пилы. По результатам экспериментов получена зависимость изменения амплитуды колебаний вала цилиндра пилы на упругих подшипниках, обоснованы параметры системы.

Keywords: Saw gin, Cylinder, Shaft, Bearing, Rubber Support, Vibration, Bending, Stiffness, Amplitude, Frequency, Mass.

Ключевые слова: пила, цилиндр, вал, подшипник, резиновая опора, вибрация, изгиб, жесткость, амплитуда, частота, масса.

Introduction. It is known that during operation, the gin saw cylinder bends, as a result of which technological gaps are violated, which negatively affects the gining process. The bending of the saw cylinder is mainly due to the large mass of the unbalanced inertial forces, as well as due to the large length of the shaft. At the same time, an analysis of the structural elements of existing structures of saw cylinders is given.

The gin saw cylinder used in production is known to contain a shaft, saw blades mounted on it with tabs that enter the shaft groove, inter-saw pads, washers and clamping nuts [1, 2]. The disadvantage of this design is a significant deflection of the shaft, leading to a change in technological inter-saw distances and gaps, high power consumption due to the massiveness of the saw cylinder, which lead to damage to the fibers and seeds of cotton, as well as to a decrease in the productivity of the gin.

 In another design of the gin saw cylinder, there is a shaft, saw blades and inter-saw gaskets, which are made with an eccentric installation of their geometric axis relative to rotation, and the geometric axes of the gaskets are arranged in a helical line along the axis of rotation of the gin saw cylinder [3, 4, 5]. The disadvantage of this design is also the massiveness of the saw cylinder, as well as significant reaction forces in bearing supports due to cyclic changes in the unbalanced masses of the system [6].

The main part. In the construction of a saw drum of a fiber-processing machine containing a shaft with at least one protrusion located on its surface, saw blades with inter-saw pads mounted on the shaft and a means for creating angular movements of saw blades are made in the form of a rubberized coating located on the protrusion and gaskets are made in the form of thrust bearings mounted on the shaft by means of bushings elements with profile grooves corresponding in shape and number to the protrusions of the shaft [7]. The disadvantage of this design of the gin saw drum is also the massiveness and complexity of the design.

The saw drum design of the fiber-processing machine [8, 9, 10] contains a shaft with at least one protrusion located on its surface, discs mounted on the saw shaft with inter-saw pads made in the form of thrust bearings mounted on the shaft by means of sleeve elements with profile grooves corresponding in shape and number to the protrusions of the shaft, and a tool for creating angular movements of saw blades, made in the form of a rubberized coating located on the protrusions of the shaft, while by performing forced torsional vibrations with each saw blade due to mixing the center of mass of each saw blade relative to the geometric axis of the shaft, through holes are made in the body of each saw blade, and the holes of adjacent discs differ in size, number, configuration and location. The disadvantage is the complexity of the design, as well as the massiveness of the saw drum [11, 12, 13].

To improve the reliability of the gin saw cylinder, resource saving and productivity, a new saw cylinder design has been developed, in which the task is solved by reducing weight and improving the design [14, 15, 16, 17, 18].

The essence of the proposed design lies in the fact that the gin saw cylinder contains a shaft, saw blades with tabs mounted on it are made symmetrically on both sides, enter the corresponding grooves of the shaft, which is made in the form of slots having transitional rounding in the bases of the hollows of the shaft, spacers, washers and clamping nuts. Making the shaft slotted (in the form of longitudinal grooves) allows you to significantly reduce the weight, while maintaining the bending stiffness of the shaft due to the slots (stiffeners), ensure resource conservation, increased reliability and obtaining cotton fiber with the necessary quality indicators.

The design is shown in the drawing (Figure 1), where, in Fig. 2, a is the general view of the gin saw cylinder, b is the section A of the shaft and c is the saw blade with tabs. The design consists of a slotted (longitudinal grooves) shaft 1, saw blades 2 with tabs 3 mounted on it, made symmetrically on both sides, entering the corresponding grooves 4 on the surfaces of the slot 5 shaft 1. At the same time, transitional rounding 6 are made in the bases of the slot 5 shaft 1, allowing an increase in the strength of the slot 5. There are spacers 7 between the saw blades 2, which are clamped on both sides of the shaft 1 with washers 8 and clamping nuts 9.

Figure 1. Design diagram of a saw cylinder with a lightweight shaft in the form of longitudinal slotted grooves

The design works as follows. During operation, when feeding raw cotton, saw blades 2 grab strands of fibers and drag them behind the grates, a strand of fibers is detached from cotton seeds. Reducing the weight of the gin saw cylinder by making the shaft 1 slotted, ensures bending of the shaft 1 within acceptable limits, allows the required process of cotton fiber separation, reduces the required gin power. The execution of saw blades 2 with tabs 3 on both sides symmetrically and grooves 4 on the corresponding slots 5 of the shaft 1 during operation leads to a kind of balancing of the masses of the system relative to the axis of rotation (to the absence of imbalance). The transitional rounding 6 on the bases of the slot 5 of the shaft 1 leads to an increase in the strength and reliability of the gin saw cylinder [19, 20, 21, 22, 23].

The recommended design allows for increased reliability, reduction of the required gin power, high-quality cotton fiber and high productivity are obtained.

 Figure 2 shows lightweight shafts with longitudinal slotted grooves.

The essence of the design lies in the fact that the gin saw cylinder contains a shaft mounted on it, saw blades with tabs are made symmetrically on both sides, entering the corresponding grooves of the shaft, which is made in the form of a slot having transitional rounding in the bases of the hollows of the shaft, spacers, washers and clamping nuts.

In this case, the grooves and protrusions and protrusions (slot) of the shaft are made at a certain angle and axis of the shaft, and the thickness of the protrusions (slot) is variable, with the largest thickness falling towards the middle along the length of the shaft, and the smallest thickness falls on both edges of the shaft. This design of the slots (protrusions and grooves) reduces the weight of the shaft and actually significantly aligns the bending of the shaft along its entire length. This allows the necessary rigidity of the shaft, leading to resource conservation, increased reliability and production of cotton fiber with the necessary quality indicators.

The design is explained in Drawing 2, where, in Figure 2 a – a general view of the gin saw cylinder, 2b – section A-A 2b – saw blade with tabs, 2g – spline shaft (part).

The design consists of a spline shaft 1, saw blades 2 mounted on it with tabs 3 made symmetrically on both sides, entering the corresponding grooves (4) on the surfaces of the slots 5 (projections) of the shaft 1. At the same time, transitional rounding is performed in the bases of the projections 5 (slots) and grooves (6) of the shaft (1) 7, allowing to increase the strength of the protrusions 5. Between the saw blades 2, there are spacers 8, which are clamped on both sides of the shaft 1 with washers 9 and clamping nuts 10. In this case, the grooves 6 and the protrusions 5 (slot) of the shaft are made at a certain angle to the axis of the shaft 1, the thickness of the protrusions 5 (slot) is variable, with the largest thickness falling to the middle along the length of the shaft 1, and the smallest thickness falls on both edges of the shaft 1.

The design works as follows. During operation, when feeding raw cotton, saw blades 2 grab strands of fibers and drag them behind the grates, the strands of fibers are detached from cotton seeds. Reducing the weight of the gin saw cylinder by making the shaft 1 slotted (protrusions 5 and grooves 6) ensures bending of the shaft 1 within acceptable limits, allows the required process of cotton fiber separation, reduces the required gin power. The transitional rounding 7 on the bases of the protrusions 5 and grooves 5 of the shaft 1 lead to an increase in the strength and reliability of the gin saw cylinder. The execution of the protrusions 5 and grooves 6 (slot) of the shaft 1 at an angle to the axis of the shaft 1 and the variability of their thickness reduce the mass of the shaft and actually significantly aligns the bending of the shaft along its entire length. This ensures the necessary rigidity of the shaft.

Figure 3. Recommended design of the gin saw cylinder

Conclusion

1. Based on the analysis of the operation of saw gins, it was revealed that the main working body of the saw cylinder bends and this negatively affects the gining technology. Due to the vibrations of the saw cylinder, the bearing supports quickly fail.
2. New efficient designs of gin saw cylinders with lightweight shafts made with longitudinal and inclined slot grooves are proposed.
3. Effective design schemes of elastic bearing supports of gin saw cylinders have been developed, allowing significant absorption of shaft vibrations, reducing damage to cotton fibers and seeds, increasing the service life of bearing supports and the saw cylinder.

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