RU2025228C1 - Sealing device for shafts and axles - Google Patents

Abstract

FIELD: rolling. SUBSTANCE: sealing device has sealing bush with taper inner polymer surface and contact labyrinth centrifugal sealer mounted on the shaft inside the sealing bush. Sealing edges of the sealer are engageable with taper polymer surface of the bush. Inner taper surface of the sealing bush is inclined relative to longitudinal axis of the shaft at angle α= 5 to 15 deg. Device is provided with wear compensators for adjusting the specific pressure in the sealing zone and secondary sealer which is used to ensure tight joint between cover of the drum and sealing bush. EFFECT: enhanced reliability. 3 cl, 3 dwg

Description

 The invention relates to mechanical equipment for rolling shops of metallurgical plants.

 Known sealing devices in which the contact-labyrinth centrifugal sealant is mounted on the shaft in a fixed position, and the sealing edges interact with the cylindrical surface of the counterbody (Kononenko A.P. and Golubov Yu.N.). Sealing devices of machinery and equipment. Calculation and design. M.: Engineering, 1984, 104 s, p. 67).

 The disadvantages of such sealing devices are the inability to control the specific pressure in the contact zone, which leads to the appearance of identical loads on the sealing edges, the inability to use such an important characteristic of the contact-labyrinth centrifugal sealant as redundancy, which leads to accelerated wear of the sealing devices, and therefore bearings rolling.

 The closest to the invention in technical essence and the achieved effect is a sealing device of a conveyor belt roller, including a contact-labyrinth centrifugal sealant, mounted on the roller axis by a sleeve, the sealing edges of which interact with interchangeable inserts (bushings), the inner surfaces of which are conical with the possibility of creating different specific pressures in the sealing zone of each HA [2].

 The disadvantage of this design is the inability to control the specific pressure of the sealing edges as they wear and grease leaks.

 The aim of the invention is to ensure reliable sealing by creating a stable specific pressure of the HA on the sealing sleeve and increasing the life of planetary scissors.

This is achieved by the fact that the sealing device for shafts and axles containing a contact labyrinth centrifugal sealant with sealing edges interacting with the conical polymer surface of the sealing sleeve, forming a contact labyrinth. In this case, the conical polymer surface of the sealing sleeve is inclined to the longitudinal axis of the shaft at an acute angle α = 5 ... 15 ^about .

 In addition, it is equipped with wear compensators for regulating the specific pressure in the sealing zone and a secondary sealant located in the annular groove made on the outer surface of the sealing sleeve.

 In FIG. 1 shows a sealing device for a small cutting head of planetary scissors; figure 2 - contact-labyrinth centrifugal sealant; figure 3 is a graph of the intensity of wear of the sealing edges depending on the angle of inclination of the inner surface of the sealing sleeve.

 The sealing device consists of a contact-labyrinth centrifugal sealant 1, rigidly mounted on the shaft 2, and a sealing sleeve 3 mounted on a movable landing in the cover 4 of the scissors drum. The sealing sleeve 3 has an antifriction polymer coating 5, and on its outer surface a secondary sealant is installed - a ring 6 of elastomer. Between the protective cover 7 and the sealing sleeve 3 installed compensators 8 wear.

 When the drum rotates, centrifugal forces arise that move the body mass from the axis of rotation to the periphery, to the end machines of the drum, causing oil pressure on these surfaces. This oil pressure also acts on the surface of the contact-labyrinth centrifugal sealant. Moreover, in statics, lubricating oil is kept from leakage due to the elastic forces of the elastomeric disks, which create the necessary degree of sealing due to the axial movement of the counterbody. When the drum rotates, the specific pressure in the sealing zone increases due to centrifugal forces acting on the sealing edges.

или I=K

, где К - коэффициент пропорциональности, зависящий от шероховатости поверхности контртела (для полимерного покрытия К = 0,03); f - коэффициент трения скольжения (резина по полимерному покрытию f = 0,51); q - удельное давление в зоне герметизации; σ_p - предел прочности на разрыв; t - коэффициент динамической выносливости, принимаемый для резин от 3 до 6; σ_o - параметр фрикционной выносливости (резина по полимерному покрытию σ_o= 5,7 даН/см²).The choice of the angle of inclination α was based on the fact that at α≅ 5 ^{о the} specific pressure of all sealing edges is caused by both the elastic forces of the elastomeric disks and dynamic loads, which lead to their identical wear and, consequently, to loss of sealing. And when α≥15 ^about sharply increases the wear rate of the sealing edges, determined by the analytical dependence
I = k

or I = K

where K is the coefficient of proportionality, depending on the surface roughness of the counterbody (for a polymer coating K = 0.03); f is the coefficient of sliding friction (rubber on the polymer coating f = 0.51); q is the specific pressure in the sealing zone; σ _p - tensile strength; t is the dynamic endurance coefficient adopted for rubbers from 3 to 6; σ _o - parameter frictional endurance (rubber on a polymer coating σ _o = 5.7 daN / cm ² ).

3
По полученным значениям интенсивности износа герметизирующих кромок построена кривая в зависимости от угла наклона внутренней поверхности уплотняющей втулки. Как видно из графика при α≥15^оинтенсивность износа герметизирующих кромок резко возрастает и, тем самым, ограничивается применение конусных поверхностей с углом наклона более 15^о.The following are the calculations of the wear rate of the sealing edges of the contact-labyrinth centrifugal sealant made of oil-resistant rubber:

3
Based on the obtained values of the wear intensity of the sealing edges, a curve is constructed depending on the angle of inclination of the inner surface of the sealing sleeve. As can be seen from the graph at α≥15 ^about the wear rate of the sealing edges increases sharply and, thereby, the use of conical surfaces with an inclination angle of more than 15 ^{about is} limited.

 During rotation of the drums of planetary scissors, the force of the mass of oil in the volume of the cutting heads exerts increased (excessive) pressure on the sealing device. With an increase in the rotational speed of the drums, centrifugal forces also increase, causing additional specific loads that increase the degree of sealing of the contact-labyrinth centrifugal sealant. In existing designs of sealing devices (cuffs according to GOST 8752-70), specific pressure can be created only through the use of bracelet springs.

 The calculation of the specific pressure created in the contact zone of the sealing device as a traditional (cuff), and the proposed contact-maze centrifugal sealant.

 Initial data: assembly drawing of a drum of planetary scissors. The frequency of rotation of the electric motor is 400 rpm; the gear ratio of the drive is 2.67.

=

= 0,735 тс, или С = 735 кгс. Здесь d торцовая поверхность режущей головки; h - длина картера режущей головки; γ - объемная масса (удельная), равная 0,9 тс/м³.The force of the weight of oil in the volume of the cutting head
C =

=

= 0.735 tf, or C = 735 kgf. Here d is the end surface of the cutting head; h is the length of the crankcase of the cutting head; γ is the bulk density (specific) of 0.9 tf / m ³ .

где m - масса масла, V - окружная скорость.The point of application of centrifugal force (mass of oil) when working with scissors
r = 835.5 m
Centrifugal force
F $\genfrac{}{}{0ex}{}{\text{and}}{\text{P}}$ ⁿ =

where m is the mass of oil, V is the peripheral speed.

=

= 15,68 c^-1 где n _б - число оборотов барабана, n_б =

=

= 149,8 об/мин Тогда
F $\genfrac{}{}{0ex}{}{\text{и}}{\text{п}}$ ^н =

= 15386 кгс/с
Давление масла на стенки картера
P =

h =

h, где f_к - площадь внутренней поверхности картера
f_к= 2

+πr_кh= 2,0·785·1,055²+3,14·0,5275·0,935= 3,295 м² Итак P =

+0,9·1,055=5,62 тс/м² или Р = 0,562 кгс/см²
Давление на торцевую поверхность герметизирующей кромки
Р = р ˙ f_г где f_г - площадь герметизирующей кромки, воспринимающей давление масла
f_г =

(D²-d²)=0,785/43²-39,6²/220,46 см² Тогда
Р = 0,562˙220,46 = 123,9 кгс.m = G / g = 735 / 9.81 = 74.92 kg.s / m,
V = r ω = 0.8355˙15.68 m / s. Here
ω =

=

= 15.68 s ^-1 where n _b is the number of revolutions of the drum, n _b =

=

= 149.8 rpm Then
F $\genfrac{}{}{0ex}{}{\text{and}}{\text{P}}$ ⁿ =

= 15386 kgf / s
Crankcase oil pressure
P =

h =

h, where f _to - the surface area of the crankcase
f _to = 2

+ πr _to h = 2.0 · 785 · 1.055 ² + 3.14 · 0.5275 · 0.935 = 3.295 m ² So P =

+ 0.9 · 1,055 = 5.62 tf / m ² or P = 0.562 kgf / cm ²
Pressure on the end surface of the sealing lip
P = p ˙ f _g where f _g is the area of the sealing edge, perceiving oil pressure
f _g =

(D ² -d ² ) = 0.785 / 43 ² -39.6 ² / 220.46 cm ² Then
P = 0.562-220.46 = 123.9 kgf.

=

= 0,917 кгс/см, где L_r = π D = 3,14˙43 = 135 см.Specific Pressure Per Sealing Edge
q =

=

= 0.917 kgf / cm, where L _r = π D = 3.14˙43 = 135 cm.

So, the oil pressure that the sealing edges must hold, exceeds the specific pressure created by the bracelet spring of 0.07 ... 0.1 kgf / cm ² more than 9 times.

=

=2,1 кгс/см Здесь Q - осевая сила, действующая по периметру герметизирующих кромок и равная 50 кгс, α = 10^о - угол наклона радиальной поверхности контртела.The specific pressure created by the sealing edges of the contact-labyrinth centrifugal sealant by the elastic forces of the material of the sealing device
q ′ =

=

= 2.1 kg / cm where Q - an axial force acting along the perimeter sealing edge 50 and equal kgf, α = ¹⁰ ° - angle radial surface opposing member.

 A comparison of the specific pressures of the mass of oil on the sealing edges of the cuff and the contact-labyrinth centrifugal sealant shows that the proposed sealing device has a more than 9-fold safety margin against loss of tightness.

 The proposed design of the sealing device has several advantages: stability against excessive oil pressure is regulated by wear compensators; reliable sealing is created by axial movement of the sealing sleeve and the contact labyrinth; the design has the property of redundancy, i.e. this property provides a probability of failure-free operation by more than 1.5 times; loss of lubricating oil is excluded.

Claims (3)

1. A SEALING DEVICE FOR SHAFTS AND AXES, containing a sealing sleeve with an internal conical polymer surface and mounted on the shaft contact-labyrinth centrifugal sealant with sealing edges mounted to interact with the conical polymer surface of the sealing sleeve, characterized in that the inner conical surface the sleeve is inclined to the longitudinal axis of the shaft at an angle of 5 - 15 ^o .  2. The device according to claim 1, characterized in that it is equipped with wear compensators for regulating the specific pressure in the sealing zone.  3. The device according to p. 1, characterized in that it is equipped with a secondary sealant located in the annular groove made on the outer surface of the sealing sleeve.

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