RU2546447C2 - Insole with anti-fretting properties - Google Patents

Abstract

FIELD: personal use articles.

SUBSTANCE: in the insole, in the zone of the heads of metatarsal bones and the big toe, where maximum loads during repulsion occur, one cuts (from the front side of the insole) slots having an inclined surface creating conditions for nonslip of the foot relative to the insole. Such structure of the insole allows to use materials in friction couples of foot (sock) - insole with friction coefficient 40% less as compared to that in case of usage of a flat insole thus to eliminate negative consequences appearing in the process of flat insoles usage. For nonslip effect intensification the slots inclined surfaces are dishevelled.

EFFECT: improvement of insole structure where in the back push phase fretting-wear conditions do not take place; such conditions negatively affect the insole and cause foot chafing.

4 cl, 5 dwg, 1 tbl

Description

The technical field to which the invention relates is the shoe industry, namely the construction of the main insole, which prevents fretting wear during shoe wear.

State of the art

Fretting wear occurs between tightly set surfaces exposed to small amplitude cyclic motion. The wear rate increases during the work of bodies in contact in an aggressive environment, in particular during perspiration.

In shoe practice, an insole is used with an almost flat section in the nose-beam part (Shoe Handler Mikheeva EA, Morekhodov GA Publ.: Legprombytizdat, 1989, 416 pp.). The support of the foot on the toe-beam part of the insole occurs during the backward push, which begins when the position of the center of mass of the human body goes forward beyond the foot support area, while the leg extends, and the support reaction force increases.

At the time of the posterior shock, the reaction force of the support increases with an increase in the speed of extension of the supporting leg in the knee joint. The maximum reaction force of the support during the rear shock is achieved when the vector directed to the common center of mass makes an angle equal to 20 ° with the vertically directed component of the force.

The reaction of the support R can be decomposed into a normal force N, perpendicular to the horizontal supporting surface, and a driving force F _dv directed horizontally. Driving force F _dv. can realize its function of horizontal displacement of the common center of mass of the human body (OCM), provided that it is less than or equal to the force of friction of the foot on the insole, i.e. when performing F _dv ≤F _Tr . Otherwise, the toe-beam part of the foot, when repelled in the phase of the back push, will slip along the insole in the opposite direction to the horizontal movement of the MTC.

The friction force F _Tr is found, in the general case, as the product of the normal force N by the friction coefficient µ i.e. F _mp = N × µ.

The value of the coefficient of friction will be determined by pairs of materials, as shown in the table below.

Table Friction coefficients of friction pairs of materials Insole material Sock material foot wool cotton nylon Bakhtarma Faux Leather 0.48 0.41 0.34 Cardboard cardboard 0.36 0.35 0.22 Leather 0.17 0.21 0.11 0.17

As can be seen from the table, the stealth-kapron skin and stealth-foot skin pairs have friction coefficients µ = 0.11 and 0.17, and, accordingly, friction forces with a lower rate than the driving force in the maximum loading position with a back push, t .e. the foot will slip over the surface of the insole.

The table also shows a pair of friction (bakhtarma of elder skin-cotton), in which the coefficient of friction µ = 0.41 and, accordingly, the friction force is slightly higher than the driving force. In most cases, with this pair of friction, the foot will not slip on the insole surface. However, the friction force and the driving force have a dispersion of their values due to the inconstancy of the properties of the surfaces of the pairs, the geometric relationships of the human body, etc.

The distribution density functions for the friction force and the driving force are determined characteristics. Their graphic representation is represented by dome-shaped curves, the intersecting zones of the corresponding distributions reflect the probability that the driving force exceeds the friction force.

When the forces under consideration are distributed according to the normal law, the probability that the value of a random variable will be greater than the value of the friction force is determined as:

where P ₁ and P ₂ are intersecting distribution zones;

F _k - the abscissa of the intersection of the distribution curves f [F _dv ] and f [F _Tr ];

f [F _dv ] - the curve of the distribution density of the driving force F _dv ;

f [F _Tr ] - the curve of the density distribution of the friction force F _Tr ;

и $${\overline{F}}_{тр}$$

- средние значения движущей силы и силы трения; $${\overline{F}}_{d\mathrm{at}}$$

and $${\overline{F}}_{tR}$$

- average values of the driving force and the friction force;

S _dv and S _tr - the standard deviation of the driving force and friction force.

If we substitute the numerical values of the parameters of typical friction pairs, the material of the toe and the insole material, then the probability of slipping of the forefoot with a back push can reach 5%. The possibility of slipping increases with the natural release of foot sweat. In this case, the dry friction between the plantar part of the forefoot and the insole material is replaced by semi-liquid or even liquid, in which the friction coefficient decreases sharply, which ensures the movement of the forefoot relative to the insole.

Thus, the three factors listed below provide, in the predominant number of cases, the relative sliding of the front section on the insole surface when walking:

- excess of the driving force of the forefoot of the foot of the friction force of individual materials of the sock on the surface of the insole;

- a certain probability of the occurrence of relative slippage in pairs of friction materials of the sock-insole with some excess of the average value of the friction force over the average value of the driving force;

- excess of the driving force of the magnitude of the forces of semi-liquid and liquid friction of the pairs of feet (toe) -insole with the manifestation of natural perspiration of the foot when walking.

The value of the relative slip does not exceed a few millimeters, since there is a constructive limiter in the form of a shoe back. Sliding occurs at a sufficiently high pressing force exceeding mg (m is the mass of the nose, g is the acceleration of gravity), the relative displacement is minimal, but repeated at each step. The combination of these impact factors is defined as the fretting wear of the contacting pairs of bodies.

Fretting wear is fraught for both bodies of a slip pair. On the plantar part of the foot, due to friction with significant pressure, there are abrasions, lesions of the skin of the foot, soreness in the area of mechanical irritation, the possibility of the formation of water corns, various pathogens penetrate. On the surface of the insole, a color change occurs, the covering layer of the insole material is abraded, the parts are damaged with the formation of cracks. The process is exacerbated by the accompanying friction of the sweating of the foot.

The constructive solutions used in practice for the stealth knot, including the prototype, do not solve the issue of eliminating the conditions for the appearance of fretting wear, which has negative consequences for both the foot of the wearer and the insole.

The required technical result

It is necessary to provide conditions for the absence of displacement of the forefoot relative to the insole with a back push during walking, which is physically achieved if the horizontal driving force throughout the considered phase of the back push is less than the friction force of the pair of the front foot insole.

The condition must be met when stopping in a sock and without a sock; with a dry foot and wet from sweat. If the driving force exceeds the value of the friction force, fretting wear occurs with negative consequences for both the foot and the insole.

SUMMARY OF THE INVENTION

To provide the invention with a technical result — the elimination or, in any case, reduction of the possibility of conditions for the occurrence of fretting wear, which occurs when there is significant pressure between the bodies making up the friction pair and their slight displacement, within a few millimeters, relative to each other, it is proposed change the geometry of the insole in the area of its contact with the heads of the metatarsal bones and the first finger.

The reason for choosing the above zones is that the maximum pressure of the forefoot in the phase of the back push is formed in the pressure planograms in these zones, that is, according to the planograms from the dissertation of Kuznetsova EA “Study of depreciation of the man-foot-support system” of Kazan State Technological University in 2009, these sections of the foot carry the main load for transmitting movement to the human body.

In the insole from the front surface, a figured groove ~ 2-3 mm deep located between the sides of the insole is cut out. The horizontal plane of the upper part of the groove is determined by the location of the heads of the metatarsal bones.

проводится дуга, соединяющая боковые стороны стельки. Образовавшаяся дуга является осью горизонтальной плоскости паза. Ширина паза образовывается между проведенными граничными дугами из найденного центра радиусам R_1,2=R±0,083Д. Нижняя поверхность паза состоит из наклонной плоскости с углом наклона $$\theta =arctg\frac{2h_1}{l_1}$$

(где h₁ - глубина подплюсневого паза в зоне его поперечной оси, l₁ - ширина подплюсневого паза равная 0,166Д), начинающейся от линии внутренней стороны полосы, проведенной радиусом R₁=R-0,083Д и заканчивающейся на середине нижней поверхности паза. Другая составляющая нижней поверхности паза представляет собой дугообразную в профиле поверхность, проходящую между серединой нижней поверхности паза и дугой наружной поверхности стельки, очерченной радиусом R₂=R+0,083Д. Радиус дуги профиля поверхности составил r₁=0,17Д, который соединяет конец наклонной плоскости в середине нижней поверхности паза с внешним контуром дугообразной полосы, расположенным на верхней плоскости паза.Geometrically, it is constructed as follows. On the continuation of the cross section 0.18 D (D is the length of the foot) from the inside of the point of intersection with the longitudinal axis (the graphic axis of the insole construction), a length of 0.13 D is laid out. From its end radius $$R=\sqrt{{(0.13D)}^2+{(0.72D-0.18D)}^2}$$

an arc is drawn connecting the sides of the insole. The resulting arc is the axis of the horizontal plane of the groove. The width of the groove is formed between the drawn boundary arcs from the found center to the radii R _1,2 = R ± 0,083D. The bottom surface of the groove consists of an inclined plane with an angle of inclination $$\theta =arctg\frac{2h_{\mathrm{one}}}{l_{\mathrm{one}}}$$

(where h ₁ is the depth of the tarsal groove in the area of its transverse axis, l ₁ is the width of the tarsal groove equal to 0.166D), starting from the line of the inner side of the strip, drawn with a radius R ₁ = R-0,083Д and ending in the middle of the lower surface of the groove. Another component of the lower surface of the groove is an arcuate surface in the profile, passing between the middle of the lower surface of the groove and the arc of the outer surface of the insole, defined by the radius R ₂ = R + 0,083Д. The radius of the arc of the surface profile was r ₁ = 0.17 D, which connects the end of the inclined plane in the middle of the lower surface of the groove with the outer contour of the arcuate strip located on the upper plane of the groove.

With a back push, the value of pressure falling on the first toe is commensurate with the same indicator in the areas of the heads of the metatarsal bones

To ensure the stability of the position of the foot on the insole and to avoid slipping on the front side of the insole, the plane of the surface of the insole under the first finger is replaced by a curly one.

On the insole at a distance of 0.9D in the area of the first finger, a line is drawn perpendicular to the longitudinal axis of the insole. From the point of their intersection towards the first finger, a segment equal to 0.16 Ш _0.68 (Ш _0.68 is the insole width in the mid-beam part) is laid out on the 0.9D line. From the point at which the delayed segment ends, a ray is drawn to this segment at an angle φ (for the normal position of the first finger, φ = 75-90 °). On a beam drawn to both sides of the segment, two segments of length 0.055 D are laid off from the intersection point, forming the axis of the figured sub-fingered groove.

к верхней плоскости паза, отклоненной по часовой стрелке, где h₂=3 мм - глубина паза, (допустимый размер углубления первого пальца, не приводящего к изменению стереотипа походки человека). Такая же глубина паза принята в зоне головок плюсневых костей. Другая сторона плоскости ограничивается серединой фигурного паза. Поверхность дугообразного профиля начинается от границы наклонной плоскости, находящейся в середине нижней поверхности фигурного паза, и заканчивается граничной линией верхней плоскости фигурного паза. Радиус дугообразного профиля равен длине верхней плоскости паза r=0,11Д.On both sides, perpendicular to the axis of the curly sub-finger groove, two lengths of 0.1 S _0.68 are laid out - the width of the sub-finger groove, the ends of the segments are connected perpendicularly forming a rectangle of the upper plane of the curly groove 0.2 S _0.68 * 0.11 S _0.68 . In the upper part of the groove, a curved arc limits the line of the outer border of the groove. The lower part of the figured groove is formed by an inclined plane and the surface of the arcuate profile starting from the rear border of the upper plane of the groove, passes at an angle $$\Psi =arctg\frac{h_2}{0.055D}$$

to the upper plane of the groove, deflected clockwise, where h ₂ = 3 mm is the depth of the groove, (the permissible size of the recess of the first finger, which does not lead to a change in the stereotype of a person’s gait). The same groove depth is adopted in the area of the heads of the metatarsal bones. The other side of the plane is limited by the middle of the figured groove. The surface of the arcuate profile starts from the boundary of the inclined plane located in the middle of the lower surface of the figured groove, and ends with the boundary line of the upper plane of the figured groove. The radius of the arcuate profile is equal to the length of the upper plane of the groove r = 0.11D.

Consider the moment of maximum loading in the phase of the rear shock. At the moment of maximum repulsion force of the foot from a flat horizontal surface, as occurs with the insole adopted as a prototype, the angle between the vertical and the direction of the resulting force is an angle α = 20 °.

Normal force is defined as N = F _Σ × cosα,

where F _Σ is the resulting force. The repulsive force equal to the driving force, but opposite to the directed one, will be F _from. = F _Σ × sinα. For the implementation of human movement, it is necessary that the horizontal driving force be less than the friction force. Otherwise, the foot will slip on the surface of the insole and there will be no transmission of movement to the human body.

The friction force is defined as F _Tr = N × µ = F _Σ cosα × µ,

where µ is the coefficient of friction of the contacting pair, i.e. sock material insole.

Considering that the driving force F _{dv is} numerically equal to the horizontal repulsive force F _from , we can write down the walking condition without slipping:

F _from. <F _tr

F _Σ sinα <F _Σ cosα × μ

tgα <µ

The angle α is determined by the geometry and distribution of the human body mass, i.e. the position of the common center of mass (GCM). For an average man, you can take the angle α equal to ~ 20 °, then tgα = 0.36. In the table of friction coefficient values for a number of typical pairs: toe materials - insole materials, the inequality tgα <µ is not observed, i.e. it is possible to slip the foot a short distance until the shoe back becomes an obstacle to further displacement of the foot relative to the insole surface.

Also, variations in the location of the JCM depending on the growth and mass of individual protruding parts of the body, for example, the abdomen, the appearance of a fluid layer between the contacting foot and the insole, etc., contribute to the violation of the established condition of the foot contact with the insole without slipping.

In the proposed design of the insole, an even horizontal surface of the insole, in the contact zone of the foot along the strip of the heads of the metatarsal bones and the first finger, is replaced by curly grooves, which are an inclined plane in the half of the lower part, and an arcuate surface that mates with the inclined plane in the second half of the lower part the first half of the lower part of the groove and the beginning of the horizontal plane of the insole.

The foot extends as much as possible at the moment of full support of the human body, which precedes the back push. When the foot enters the phase of the back push, when its front section is advanced forward to the maximum value, the heads of the metatarsal bones are located on the inclined plane of the tarsal groove, and the distal phalanx of the first finger is on the inclined plane of the subdigital groove.

.Given that the strip of the upper plane of the groove has a width of 0.17 D and the depth of the groove h ₁ = 3 mm, the angle of inclination of the lower plane of the groove for the insole of medium-sized men's shoes will be $$\theta =arctg\frac{2h_{\mathrm{one}}}{0.17D}=8^{\mathrm{about}}$$

.

от этой поверхности.The foot zone of the heads of the metatarsal bones will not repel from the horizontal plane, as in the prototype, but from the plane inclined at an angle θ = 8 °. A rotation of the horizontal plane by an angle θ = 8 ° will change the distribution of the resulting force F _Σ by the force normal N ′ ′ to the new surface and the force repelling $$F_{\mathrm{about}t}^{\text{'}\text{'}\text{'}\text{'}}$$

from this surface.

The angle between the resulting force F _Σ and the normal force N ″ will be γ = α-θ = 20 ° -8 ° = 12 °.

.The new normal force is N ′ ′ = F _Σ cosγ. Given that the resulting forces when using the prototype insoles and the proposed design are the same in magnitude, their values are taken as unit, i.e. F _Σ = 1, and then N ′ ′ = 1 × cos12 ° = 0.98. The new driving force will be $$F_{\mathrm{about}t}^{\text{'}\text{'}\text{'}\text{'}}=F_{d\mathrm{at}}^{\text{'}\text{'}\text{'}\text{'}}=F_{\Sigma }\sin \gamma =\mathrm{one}\times \sin {12}^o=0.21$$

.

The conditions for repelling the foot without slipping on the surface of the insole in the phase of the back push will be written:

$$F_{d\mathrm{at}}^{\text{'}\text{'}\text{'}\text{'}}<F_{tR.}$$

tgγ <µ ^I ,

where µ ^I is the coefficient of friction for an inclined plane.

Since the angle γ is 12 ° for an inclined repulsion plane, then slippage will not occur if

µ ^I > 0.21

. Аналогичный результат получается при расчете условия ходьбы без проскальзывания для первого пальца.With a horizontal repulsion plane without slipping, the friction coefficient must fulfill the condition µ> 0.36. Changing the angle of inclination of the repulsion plane expands the lower limit of the coefficient of friction by 42%: $$\frac{\mu -{\mu }^I}{\mu }\times \mathrm{one\; hundred}\%=\frac{0.36-0.21}{0.36}\times \mathrm{one\; hundred}\%=42\%$$

. A similar result is obtained when calculating the walking conditions without slipping for the first finger.

The technical result is ensured by the construction of the tarsal and submarine grooves, in which the dimensions are increased 1.15-1.2 times and this expanded space of the grooves is filled with material with an elastic modulus of 2-5 MPa, which allows it to be compressed under pressure from the metatarsus and the first finger feet. In the phase of the back push, the supporting surface of the grooves takes the form of inclined planes, which creates the conditions for pushing the foot away from the insole without slipping, as in the case of using the grooves without filling them with other material. The use of an elastic filler of the tarsal and submalid grooves creates an additional positive effect of depreciation of the foot in the phase of the back push.

(где h₁ - глубина подплюсневого паза в зоне его поперечной оси, l₁ - ширина подплюсневого паза), начинающейся от линии внутренней стороны полосы и заканчивающейся на середине нижней поверхности паза, другая составляющая нижней поверхности паза представляет собой дугообразную в профиле поверхность, проходящую между серединой нижней поверхности паза и лицевой стороной стельки, радиус дуги профиля поверхности составляет 0,17Д, который соединяет конец наклонной плоскости в середине нижней поверхности паза с внешним контуром дугообразной полосы, расположенным на верхней плоскости паза.Thus, we present the formulated essence of the invention: an insole designed for shoes made of leather, cardboard and other materials, containing a flat leather or cardboard plate with a thickness of more than 4 mm, having the configuration of the track of the block, characterized in that on the insole, in the area of the metatarsal heads bones, there is a tarsal groove, in the upper plane it is an arched strip 0.17 D wide and an average radius of 0.56 D located between the inner and outer sides of the insole, the lower surface of for consists of an inclined plane with an angle of inclination $$arctg\frac{2h_{\mathrm{one}}}{l_{\mathrm{one}}}$$

(where h ₁ is the depth of the tarsal groove in the area of its transverse axis, l ₁ is the width of the tarsal groove), starting from the line of the inner side of the strip and ending in the middle of the lower surface of the groove, the other component of the lower surface of the groove is an arcuate surface in the profile, passing between the middle of the lower surface of the groove and the front side of the insole, the radius of the arc of the surface profile is 0.17D, which connects the end of the inclined plane in the middle of the lower surface of the groove with the outer contour of the arcuate polo sys located on the upper plane of the groove.

(h₂ - глубина подпальцевого паза в зоне его поперечной оси, l₂ - длина подпальцевого паза), проходит от близлежащего к основанию первого пальца края полосы до середины нижней поверхности подпальцевого паза, дугообразная в профиле поверхность нижней части подпальцевого паза соединяет конечную грань плоскости с передней граничной линией полосы верхней плоскости паза, при этом радиус дуги профиля поверхности нижней части паза составляет 0,11Д. Продольная ось подпальцевого паза наклонена в сторону первого пальца под углом 75-90° относительно линии сечения 0,9Д.The insole has a sub-finger groove, in the upper plane it is a strip with a width of 0.2 W _0.68 and a length of 0.11 D, the lower surface of the sub-finger groove consists of a joined inclined plane and arched in the surface profile, the inclined plane of the lower surface of the sub-finger groove has an inclination angle equal to $$arctg\frac{2h_2}{l_2}$$

(h ₂ is the depth of the fingertip groove in the area of its transverse axis, l ₂ is the length of the fingertip groove), runs from the edge of the stripe adjacent to the base of the first finger to the middle of the lower surface of the fingertip groove, the arcuate surface of the lower part of the fingertip groove in the profile connects the end face of the plane with the front boundary line of the strip of the upper plane of the groove, while the radius of the arc of the profile of the surface of the lower part of the groove is 0.11 D. The longitudinal axis of the subdigital groove is inclined towards the first finger at an angle of 75-90 ° relative to the section line 0.9D.

The insole has an enlarged 1.15-1.2 times the volumetric dimensions of the tarsal and submalid grooves filled with material with an elastic modulus much less, for example 2-5 MPa, than the elastic modulus of the insole material (80-100 MPa); the filling material, compressing, will take the old contours of the grooves, which will ensure repulsion in the phase of the rear shock without slipping and at the same time ensure the shock absorption of the rear shock.

The surfaces were tousled in inclined planes in the tarsal and subdigital grooves, which allows to increase the friction coefficient in the pairs of the foot (toe) insole from the value (0.11-0.17) to the value (0.34-0.48), which thereby expanding the lower boundary of the coefficient of friction of a pair of feet (toes) of the insole, in which the condition of repelling the foot from the insole without slipping is observed.

Summary of the invention

The problem to which the claimed invention is directed is to exclude the phenomenon of fretting wear that occurs during the phase of the back push, when the common center of mass of the human body is brought forward, and the repelling foot is located behind, resting on the insole with its front section. In this case, the maximum load falls on the area of the heads of the metatarsal bones and the first finger of the nose. The working condition of the forefoot without slipping relative to the upper surface of the insole is possible only if the driving force, which depends on the geometry of the human body, including the position of its CMF, is less than the friction force arising between the contacting surfaces of the foot and the upper surface of the insole.

Due to the variety of materials used for socks, as well as materials and coatings on the upper surface of the insole, friction pairs arise, where the conditions of non-slip are violated and the foot slips relative to the insole with every step in the back shock phase or against the shoe sole or other stopper (belt).

Low amplitude slippage under pressure on the contacting surfaces by the dynamic mass of the body causes fretting wear of the contacting pairs - abrasions on the foot and the insole surface, destruction of the toe materials.

The elimination of the possibility of fretting wear is carried out by making structural changes to the insole.

Using the pressure pattern on the insole, maximum pressure zones are identified in the back shock phase.

Such zones are the support of the heads of the metatarsal bones, located along an arcuate strip 0.17D wide, the support of the first finger.

, где h₁ - глубина паза по осевой линии, l₁ - ширина полосы (0,17Д).An axial line is drawn on the head band of the metatarsal bones and the insole material is sampled (cut out) from the inner line of the stripe to the center line along an inclined plane at an angle $$\theta =arctg\frac{2h_{\mathrm{one}}}{l_{\mathrm{one}}}$$

where h ₁ is the depth of the groove along the center line, l ₁ is the strip width (0.17 D).

The heads of the metatarsal bones fall into the cut out groove, and the repulsion plane changes, instead of horizontal, as in the prototype, it becomes inclined. Changing the inclination of the repulsion plane leads to an expansion of the lower limit of the coefficient of friction, which makes it possible to use almost all currently used pairs of friction of the foot (toe) of the insole without slipping in the back shock phase, i.e. fretting wear conditions are eliminated.

The groove for the heads of the metatarsal bones extends from the inside of the insole to the outside.

, где h₂ - глубина подпальцевого паза в зоне его поперечной оси, l₂ - длина подпальцевого паза (0,11Д).A similarly configured subdigital groove is made in the contact zone of the insole with the first finger. The back of the lower surface of the subdigital groove is an inclined plane with an angle of inclination $$\Psi =arctg\frac{2h_2}{l_2}$$

where h ₂ is the depth of the subdigital groove in the area of its transverse axis, l ₂ is the length of the subdigital groove (0.11 D).

The front part of the lower surface of the subdigital groove is an arcuate surface in the profile, starting from the end of the inclined plane of the groove and ending on the outer surface of the upper plane of the insole. The width of the subdigital groove is 0.2 W _0.68 . The radius of the arc of the profile projection of the subdigital groove is r ₂ = 0.11D.

Inclined planes of the tarsal and submalid grooves are tousled to increase the coefficient of friction of a pair of feet (toe) insoles, which expands the ability to use a wider group of pairs of materials to realize a back push without slipping.

List of drawings

Figure 1 - density distribution of the values of f [F _dv ] and f [F _Tr ].

Figure 2 is a diagram of the forces acting in the interaction of the foot and the insole (a), acting in the interaction of the foot and the insole of the proposed design (b) in the phase of the back push.

Figure 3 - the proposed design of the insole with tarsal and talus grooves.

Figure 4 - construction of the tarsal groove.

Figure 5 - the construction of the sub-finger groove.

Information confirming the possibility of carrying out the invention

The tarsal groove can be made by milling with an inclined plane with a conventional mill, the axis of which is inclined to the horizontal surface of the insole at an angle of 6-8 °; while the insole (or milling cutter) makes a relative longitudinal movement, providing an arcuate surface. The arcuate profile of the front of the groove is provided by a shaped cutter with offset teeth under a given arcuate profile. The milling cutter or insole also needs to communicate movement relative to each other to ensure the desired surface configuration.

In a similar manner, the subdigital groove is made.

The required milling machine is mass-produced.

Description of the construction of the invention in a static state

The proposed design of the insole is an external insole according to the external outline, where, at the location of the heads of the metatarsal foot in the anterior push phase, a curly sub-tarsal groove 1 is cut (Fig. 3), the upper plane of which is an arched strip 0.17 D wide. The lower surface of the tarsal groove is formed by the conjugation of the tarsal inclined plane 3, which runs along the entire length of the tarsal groove 1, and arched in the profile of the tarsal surface 4, which also runs along the entire length of the tarsal groove 1. The maximum depth of the groove is under the center line and is h ₁ = 3 mm . This value of the groove depth is selected from the conditions of maintaining the stereotype of a person’s habitual walking. The inclined plane serves to repel the metatarsal bones from the insole in the backward push phase. The geometry of the construction of the tarsal groove is given below.

The inclined plane 3 of the tarsal groove 1 and the curved tarsal surface 4 in the profile are mated along the axis in the lower part of the tarsal groove 1. The tarsal groove 1 connects the inner and outer sides of the insole (Fig. 3).

On the proposed design of the insole there is a sub-finger groove 2 located in the contact zone of the first finger with the insole.

, где h₂ - глубина подпальцевого паза в зоне его поперечной оси, l₂ - длина подпальцевого паза.The lower surface of the groove consists of a sub-fingered inclined plane 5 and an arcuate surface in the profile 6, conjugated along the axial line of the lower surface of the sub-fingered groove 2. The inclined plane 5 is located at an angle $$\Psi =arctg\frac{2h_2}{l_2}$$

where h ₂ is the depth of the subdigital groove in the area of its transverse axis, l ₂ is the length of the subdigital groove.

The length of the subdigital groove is l ₂ = 0.11 D, and its width is 0.2 W _0.68 (Fig. 4). The transverse axis of the subdigital groove is in the 0.9D sectional zone, and the longitudinal axis of the subdigital groove is at a distance from the insole axis of 0.16 Ш _0.68 at an angle of inclination φ = 75-90 ° to the horizontal axis.

The inclined plane of the subdigital groove serves to repel the first finger in the phase of the posterior push.

Description of the action (work) of the insole design

In the phase of the posterior thrust, the foot rests with the front section (metatarsal part and fingers) on the supporting surface, while the common center of mass of the human body (OCM) is advanced. According to the pressure pattern at the back push, the maximum load falls on the area of the heads of the metatarsal bones and the area of the first finger.

In the proposed design, the insoles made curly grooves - submuscular 1 and submalid 2 (figure 3). The lower surfaces of both grooves consist of conjugate inclined planes and arched in the surface profile (figure 3 and 4).

The foot in the corresponding part in the phase of the posterior tremor falls into the tarsal and submandular grooves. Since the common center of mass is substantially advanced, the insole reaction in the metatarsal region and the first finger will mainly come from inclined planes along the lines directed to the center of gravity. In this case, the normal force perpendicular to the inclined plane of the groove in the direction will approach the resulting force, and the driving force directed along the plane will decrease. As the normal force increases, the frictional force increases. In this case, the driving force directed along the inclined plane decreases, i.e. these two factors contribute to expanding the ability to not slip the foot on the insole. Thus, the possibility of using almost all the applied friction pairs of the foot (toe) -insole increases, providing repulsion in the phase of the back push without slipping.

In the phase of the backward push, the lower part of the groove, which is an arched surface in the profile, due to the geometric pattern of the direction of the acting forces, practically does not participate in the repulsion process.

Settlement and design part

In the case where F _Tr > F _dv., Slippage will not take place, however, in the case when F _Tr <F _dv. slippage and fretting wear will occur. In a situation where F _Tr ≥F _dv , in accordance with the Laplace theorem, we calculate the total probability of occurrence of slippage (Fig. 1).

The calculation is made to determine the likelihood of fretting wear in the back shock phase at the maximum value of the driving force F _dv.

Actual value of force (arithmetic mean):

Standard deviation:

и $$f({\overline{F}}_{тр})$$

, определялись численным методом F_k=173.3.Coordinates of intersection of densities bounded by graphs $$f({\overline{F}}_{d\mathrm{at}})$$

and $$f({\overline{F}}_{tR})$$

were determined by the numerical method F _k = 173.3.

The area of the curved triangle to the right of the intersection point F _k shows the probability that the driving F _dv. more friction force F _Tr (F _dv. > F _Tr ), this creates conditions for slipping of the foot relative to the insole and creates conditions for fretting wear.

The area of the curved triangle outlined by the curve f (F _Tr ) and the abscissa lying to the left of the intersection point F _k shows the probability that the friction force F _Tr will be less than the driving force F _dv (F _Tr <F _dv ), which creates conditions for slipping of the foot in the metatarsophalangeal part relative to the insole and conditions are created for fretting wear.

Given that the probabilities P ₁ (x ₁ ≥x _n ) and P ₂ (x ₂ ≤x _n ) form a group of independent events, then the total probability will be equal to:

значительно превышает движущую силу $${\overline{F}}_{дв}$$

, существует вероятность P_общ.=0,05%, когда $${\overline{F}}_{дв}>{\overline{F}}_{тр}$$

и возможно условие фреттинг износа.Thus, although the average value of the force $${\overline{F}}_{tR}$$

significantly exceeds the driving force $${\overline{F}}_{d\mathrm{at}}$$

, there is a probability P _total. = 0.05% when $${\overline{F}}_{d\mathrm{at}}>{\overline{F}}_{tR}$$

and possibly the condition of fretting wear.

Based on the fact that the greater the value of the driving force F _dv in comparison with the friction force F _Tr , the greater the likelihood of slippage, we will consider how the indicator of the driving force will change with a change in the angle of inclination of the foot (figure 2).

During the study, two cases of the position of the foot in the phase of the posterior shock were considered. For the first case, a classic prototype of a flat insole was chosen for calculation, and in the second, the inclined surface of the proposed design of the insole groove. The inclined surface is at an angle of 6 ° -8 °, the maximum depth of the groove does not exceed 3 mm.

The angle α is determined by the geometry and distribution of the human body mass, i.e. the position of the common center of mass (GCM). The resulting force F _{Σ is} directed to the OTsM in the first case at an angle α = 20 °. For the second case, the angle γ is 12 ° for a groove depth of 3 mm.

и $${\overline{F}}_{дв}^{II}$$

, а также N^I и N^II.Conditionally assuming that in the first and second case the resulting force F _Σ = 1, we find the values $${\overline{F}}_{d\mathrm{at}}^I$$

and $${\overline{F}}_{d\mathrm{at}}^{II}$$

as well as N ^I and N ^II .

The foot in the corresponding areas in the phase of the posterior tremor falls into the tarsal and submandal grooves. Since the common center of mass is substantially advanced, the insole reaction in the metatarsal region and the first finger will mainly come from inclined planes along the lines directed to the center of gravity. In this case, the normal force perpendicular to the inclined plane of the groove in the direction will approach the resulting force, and the driving force directed along the plane will decrease. Thus, the possibility of using almost all the applied friction pairs of the foot (toe) -insole increases, providing repulsion in the phase of the back push without slipping.

In the insole in the area of the heads of the metatarsal bones and the first toe, where there are maximum loads when repelled, grooves are cut from the front side of the insole with an inclined surface, which creates conditions for the foot to slip relative to the insole. This design of the insole (figure 3) allows the use of materials in pairs of friction of the foot (toe) of the insole with a coefficient of friction lower by 40% than that of a flat insole, thereby eliminating the negative effects that occur when using flat insoles.

проводится дуга, соединяющая боковые стороны стельки. Образовавшаяся дуга является осью горизонтальной плоскости паза. Ширина паза строится на пересечении граничных дуг из найденного центра радиусами R_1,2=R±0,083Д.To build a sub-tarsal groove (Fig. 4), a 0.13D length line is laid out on the inside of the 0.18D insole cross section from the intersection with the longitudinal axis O ₁ . From its end radius $$R=\sqrt{{(0.13D)}^2+{(0.72D-0.18D)}^2}$$

an arc is drawn connecting the sides of the insole. The resulting arc is the axis of the horizontal plane of the groove. The width of the groove is constructed at the intersection of the boundary arcs from the found center with radii R _1,2 = R ± 0,083D.

To ensure stability of the position of the foot on the insole and to avoid the possibility of slipping on the front side of the insole, the flat surface under the first finger changes to a figured one (Fig. 5).

To build a subdigital groove in the cross section of 0.9 D, a line is drawn perpendicular to the longitudinal axis of the insole. From the point of their intersection towards the first finger, a segment equal to 0.16 Ш _{0.68 is} laid out on the 0.9D line. From the point at which the delayed segment ends, a beam is drawn at an angle φ = 75-90 °, which is deposited from the segment. On a beam drawn in both directions, two segments of length 0.055 D, which form the axis of a figured submandal groove, are also delayed from the point of intersection. On both sides, perpendicular to the axis of the curly sub-finger groove, two lengths of 0.1 × _{0.68 are} laid, forming the width of the sub-finger groove, the ends of the segments are connected perpendicularly, forming a rectangle of the upper plane of the curly groove. In the upper part of the groove, the line of the outer surface of the groove is limited by a curved arc.

Claims (4)

1. An insole designed for shoes, having the configuration of the track of the pads made of leather, cardboard and other materials, which is a flat leather or cardboard plate with a thickness of more than 4 mm, characterized in that on the insole in the area of the heads of the metatarsal bones there is a tarsal groove, the upper plane is an arcuate strip 0.17 D wide (D is the length of the foot) and an average radius of 0.56 D, located between the inner and outer sides of the insole, the lower surface of the groove consists of an inclined plane with tilt scrap $$arctg\frac{2h_{\mathrm{one}}}{l_{\mathrm{one}}}$$

(where h ₁ is the depth of the tarsal groove in the area of its transverse axis, l ₁ is the width of the tarsal groove), starting from the line of the inner side of the strip and ending in the middle of the lower surface of the groove, the other component of the lower surface of the groove is an arcuate surface in the profile, passing between the inner and outer sides of the insole, the radius of the arc of the surface profile is 0.17D, which connects the end of the inclined plane in the middle of the lower surface of the groove with the outer contour of the arcuate strip located on erhney groove plane. 2. The insole according to claim 1, characterized in that it has a subdigital groove in the upper plane representing a strip of width 0.2W _0.68 and a length of 0.11D, the lower surface of the subdigital groove consists of a joined inclined plane and arched in the profile surface, the inclined plane of the lower surface of the subdigital groove has an inclination angle equal to $$arctg\frac{2h_2}{l_2}$$

(where h ₂ is the depth of the fingertip groove in the area of its transverse axis, l ₁ is the length of the fingertip groove), runs from the edge of the stripe adjacent to the base of the first finger to the middle of the lower surface of the fingertip groove, the arcuate surface of the lower part of the fingertip groove in the profile connects the end face of the inclined the plane with the front boundary line of the strip of the upper plane of the groove, while the radius of the arc of the surface profile of the lower part of the groove is 0.11 D, the longitudinal axis of the groove coincides with the position of the longitudinal axis of the first finger. 3. The insole according to claim 1, characterized in that the tarsal and submalid grooves enlarged 1.15-1.2 times in size are filled with material with an elastic modulus much smaller, for example 2-5 MPa, than the elastic modulus of the insole material ( 80-100 MPa), the filling material, compressing, will take on the contours of underexposed grooves, which will ensure repulsion in the phase of the rear shock without slipping and at the same time give shock absorption to the rear shock. 4. The insole according to claim 1, characterized in that its inclined surfaces of the tarsal and submalid grooves are tousled, thereby significantly increasing the friction coefficient of a pair of feet (toe) - insole and the risk of fretting wear is reduced.

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