FR2693087A1 - Shoe end reinforcement and safety shoe provided with such reinforcement. - Google Patents

Abstract

In this reinforcement a skirt (13) bent inward from the lower parts of a front end part (11b) and opposing side parts (12a, 12b) has a width gradually decreasing from the front end towards the end. rear and the inner peripheral edge (14) of the skirt (13) has an arcuate shape. A vertical wall having a central member is formed in the front end part and a connecting part between the front end part and the skirt has an arcuate shape such that the inner and outer surfaces of the arcuate part have large radii of curvature. and the lower end of the central element reaches the lower surface of the skirt.

Description

SHOE TOE REINFORCEMENT AND SHOE

SAFETY PROVIDED WITH SUCH REINFORCEMENT

  The present invention relates to a shoe end reinforcement or toe stiffener formed from a reinforced plastic material and intended to be applied to a safety shoe or other type of shoe and it relates to a safety shoe or boot using this

butt reinforcement.

  Up to now, end reinforcement 1 û has been proposed using a reinforced plastic material.

  containing carbon fibers or the like.

  However, in the conventional end reinforcement, no significant importance was attached to the mechanical resistance of the skirt part or rim part of the end reinforcement, which part is bent inwards from the part

lower end reinforcement.

  We will describe with reference to Figures 1 to 3 the conventional end reinforcement which is formed of a reinforced plastic material in which are incorporated carbon fibers or other similar fibers as described

  in published Japanese Utility Model Application No. 62-

  73706 A toe reinforcement 1 is formed so that its shape is curved along the contour of the front part of a shoe extending from the upper rear end part 1a to the front end part 1b and up to the lower parts 3 a and 3 b of side parts 2 a and 2 b and the skirt part 4 is formed so that it is bent inwards from the front end part 1b and the opposite opposite side parts 3 a and 3 b In the skirt part 4, the width X 'of the front end part is substantially equal to the widths Y', Y 'of the rear end part (X' Y ') and

  the inner peripheral edge 5 is given an arcuate shape.

  In the end reinforcement 1 which is shown in FIGS. 1 to 3, the upper side and the laterally opposite sides have a uniform and relatively small wall thickness over their entire surface area and the lateral sides extending upwards from the end part before lb and from the laterally opposite lower parts 3 a and 3 b are inclined inwards in the connection parts between the skirt part 4 and the front end lb and the lower laterally opposite parts 3 a and 3 b C '' is why, when a force P of an object falling from above is exerted on this end reinforcement, as shown in Figure 4, we are faced with the disadvantage that the empty space wrapped 5 of the end reinforcement 1 decreases in volume and subjected to pressure and shock the fingers of the user's foot as a result of the deformation of the upper side of the end reinforcement 1 giving the latter a curved shape ve rs the bottom as a function of the increase in force P and, at the same time, the skirt part 4 is displaced and deformed upwards to the point of applying additional pressure to the toes from below, as

this appears in figure 2.

  The published European Patent Application NOO 100 181 describes a toe reinforcement or shoe end stiffener which is formed from a plastic material reinforced with fibers incorporated In the toe reinforcement described in this European Patent Application, while the wall of the front end part and of the opposite side walls have a large thickness to prevent the upper side and the skirt part from being deformed by the pressure P which is exerted, as shown in FIG. 4, the skirt part which is bent towards the interior from the front end part and from the opposite side parts is bent in a substantially perpendicular direction When the end reinforcement is formed by heating and pressing with a mold a sheet of reinforced plastic, the fact that relatively long fibers, between 20 to mm, are incorporated into the plastic causes the inconvenience deny that, despite the free flow of the resin during the pressure molding operation in the connecting parts between the skirt part and the front end part and the opposite side parts, the relatively long fibers cannot flow together with the resin to uniformly maintain the ratio of their incorporation into the resin and as a result the connecting parts have a

  decrease in their mechanical strength.

  In addition, when this end reinforcement 1 is subjected to the significant load of the pressure P exerted on this end reinforcement from above, as shown in FIG. 4, for the purposes of pressure tests and pressure tests. impact, the resulting drawback is that the opposite lateral parts 2 a and 2 b deviate respectively in the direction of the arrows 6 a and 6 b and, possibly, cause the appearance of a crack 7 (FIG. 1) on the terminal part before lb. FIG. 5 is a plan view showing an end reinforcement 1 'which is described in European Patent NO 0 219 633 Although the width X "of the front end part 1b of a skirt part 4' is greater than the widths Y ", Y" of the rear end part, the inner peripheral edge 8 of the skirt part 4 ′ does not have an arcuate shape and the edge on the side of the end part

  before lb has a rectilinear shape 8 c.

  Also in this case, the fact that the large load exerted on the upper side of the end reinforcement has the effect that the opposite lateral parts 2 a and 2 b of the skirt part 4 'move outward in the direction of the arrows, a stress is concentrated in the connection parts 8 d between the arcuate parts 8 a and 8 b of the inner peripheral edge 8 of the skirt part 4 'and the straight part 8 c and gives rise to cracks 9, 9 in these last although no cracks appear in the terminal part before lb. As a result, safety shoes that use the toe caps described above have a handicap due to their lack of resistance to

  local or hollow subsidence and impact.

  The present invention therefore aims to provide an end reinforcement which is not subject to either breaking or cracking in any portion of the skirt part under the effect of a load exerted on its upper side and which also allows for a safety shoe with excellent resistance to sagging

  local or hollow formation and impact.

  These objectives are achieved using the toe reinforcement or shoe end stiffener according to the present invention. In accordance with the present invention, it is suggested that in a toe reinforcement or toe stiffener of the type formed from a reinforced plastic material in which are incorporated fibers, such as carbon fibers and glass fibers, the skirt part bent inward from the lower parts of the front end part and opposite side parts of the latter has a width which gradually decreases in a direction from the front end portion to the rear end portion and that the inner peripheral edge of

  said skirt part has an arcuate shape.

  In a preferred embodiment of the end reinforcement according to the present invention, a vertical wall part provided with a core or central vertical wall element is formed at least in the front end part of the end reinforcement, a connection part between the front end part and the skirt part has an arcuate shape so that the inner surface and the outer surface of this arcuate part both have relatively large radii of curvature (RI and R 2), and the lower end of the the central vertical wall element reaches the lower surface of said skirt portion. According to the present invention, a safety shoe or boot produced by

  use of the butt reinforcement described above.

  In the end reinforcement of the present invention, the fact that the width of the skirt part is formed so as to decrease progressively in the direction going from the front end towards the rear end of this end reinforcement and of the fact that the inner peripheral edge of the skirt part has an arcuate shape, the end reinforcement does not induce stress concentration any more than it causes a rupture or a crack in any portion of the skirt part comprising the front end part of the latter even when a significant load is exerted on the upper side of the end reinforcement and the opposite lateral parts of the end reinforcement are subjected

spacing outwards.

  In this preferred embodiment of the end reinforcement according to the present invention, since the lower end of the core or central element of vertical wall reaches the lower surface of the skirt part bent inwards, this core or central element of vertical wall prevents the upper surface part of the butt reinforcement from buckling strongly downwards or from breaking or being damaged in any other way when a heavy object falls on the upper surface part because the connecting part between the skirt part and the front end part has an arcuate shape such that the inner and outer surfaces of the arch have large radii of curvature, the relatively long fibers which are incorporated in the sheet of material reinforced plastic to be molded by being subjected to an application of heat and pressure move in a regular manner together with the r sine which is softened and which can flow in proportion to the dimensions of the empty space present between the male mold and the female mold and are distributed uniformly from the front end part and through the skirt part, the risk that the mechanical resistance of the connection part is damaged by a lack of

fiber is zero.

  The present invention will now be described more specifically with reference to the accompanying drawings, in which: FIG. 1 is a bottom view of a conventional end reinforcement made of reinforced plastic; Figure 2 is a longitudinal sectional view of the conventional end reinforcement of Figure 1; Figure 3 is a sectional view through A-A of Figure 2; Figure 4 is a sectional view showing the end reinforcement placed in a def ormed state as it takes when a load is exerted on its upper side; Figure 5 is a plan view showing another conventional end reinforcement; Figure 6 is a bottom view showing a first embodiment of the tip reinforcement according to the present invention; Figure 7 is a graph showing the relationship between the width of the front end portion of the skirt portion of the toe cap and the fracture rate of the front end portion; Figure 8 is a bottom view showing a second embodiment of the tip reinforcement according to the present invention; FIG. 9 is a perspective view showing a third embodiment of the end reinforcement according to the present invention; Figure 10 is a plan view of the end reinforcement shown in Figure 9; Figure 11 is a sectional view through B-B of Figure 10; Figure 12 is a rear view of the end reinforcement shown in Figure 10 as seen in the direction of arrow C; Figure 13 is an enlarged and partial sectional view showing the vertical wall portion shown in Figure 11; FIG. 14 is a plan view showing a fourth embodiment of the end reinforcement according to the present invention; and FIG. 15 is a side view partially in section of a safety shoe according to an embodiment

  realization of the present invention.

  We will first describe the first embodiment shown in FIG. 6. A butt reinforcement or butt stiffener 10 is made of reinforced plastic material using a nylon resin, or other similar resin, and incorporating therein. ci fibers, such as carbon fibers and glass fibers Although no visible profile of this end reinforcement has been shown, it is not particularly

  different from the classic toe reinforcement.

  In Figure 6, we see that the reference llb

  designates the front end part of the end reinforcement 10.

  The references 12 a and 12 b respectively designate the lateral parts on the little finger side and on the toe side and the reference 13 designates a skirt part formed by its bending inwards from the front end part llb and the opposite lateral parts 12 a and 12 b The inner peripheral edge 14 of the skirt part 13 has an arcuate shape The width X of the front end part llb of this skirt part 13 is greater than the width Y 1 of the rear end part on the little finger side and at the width Y 2 of the latter on the side

toe (X> Y 1, Y 2).

  More specifically, the end reinforcement 10 has a wall thickness of 2 mm, the width X of the front end portion has a value of 12 mm, the width Y 1 of the rear end portion on the little finger side has a value of 7 mm and the width Y 2 of the latter on the little finger side has a value of 9 mm This end reinforcement comprises reinforcing fibers distributed in the connection part between the upper side part and the skirt part and in the skirt part in the same way as in the conventional end reinforcement The present end reinforcement has been subjected to a pressure test The results of this test are shown in FIG. 7 FIG. 7 is a graph showing the relationship between the width X (in mm) of the front end part 11b of the skirt part 13 and the failure rate (%) that has been observed in the front end part The values shown on the graph indicate that the break rate decreases in proportion to the increase tion of the width X of the

front end part.

  FIG. 8 shows a modification that has been made to the skirt part 13 ′ of the end reinforcement shown in FIG. 6 in the sense that its width has been increased in the direction going from the front end part 11b towards the little finger side and that this width has been progressively reduced in the direction of the rear end portion The end reinforcement 10 shown in FIG. 8 is as effective in preventing a rupture of the front end portion 11b as the end reinforcement illustrated in FIG. 6 Because the tip reinforcement gradually tilts on the little finger side with respect to the toe side, the load exerted on the tip reinforcement forces it to deviate strongly on the little finger side and generates a strong stress on this little finger side, as can be seen in FIG. 4 However, this end reinforcement is not the seat of any rupture because the

  width is increased on the little finger side.

  In FIGS. 9 to 13, the reference 10 designates an end reinforcement as a third embodiment of the present invention which is made of reinforced plastic material using a nylon resin, for example, in which are incorporated relatively long fibers (20 to 50 mm) such as carbon fibers or glass fibers The end reinforcement is formed by gradually increasing the thickness of its wall from the rear end part 11a to the front end part 11b of the upper side 11 and, at the same time, the front end part 11b is transformed into a vertical wall part 16 of great thickness and the lower part 16 b of the vertical wall part 16 is bent inwards so that the skirt part 13 has a

  lower surface 17 extending in a horizontal plane.

  A connection part 18 comprised between the skirt part 13 and the vertical wall part 16 is given an arcuate shape so that the interior and exterior surfaces of the arch have relatively large radii of curvature (R 1 and R 2), as shown in FIG. 13 A central element or vertical core 16 a of the vertical wall part 16 is formed so that its lower end reaches the lower surface 17 of the skirt part 13 The vertical central element is a part which is interposed between , on the one hand, the intersection a of the lower surface 17 of the skirt part 13 with the outer arcuate surface 18 a of the connection part 18 and, on the other hand, the intersection b of the extension of the interior surface of the vertical wall part 16 with the

lower surface 17.

  The opposite side walls 12 a and 12 b curved from the upper side 11 and extending to the opposite side lower parts 15 a and 15 b are not always necessarily vertical walls When these opposite side walls 12 a and 12 b appear in the form of vertical walls, the butt reinforcement can acquire higher mechanical strength to resist

  on the impact of an object falling on this reinforcement.

  The central element or vertical core 16 mentioned above, in the embodiment illustrated in Figure 10, is formed in the vertical wall part 16 which is present only in the terminal part before llb

  and has a substantially planar shape similar to a crescent.

  This particular shape of the central element or core 16 a of vertical wall makes it possible to considerably reduce the dimensions of the end reinforcement by allowing the side walls 12 a and 12 b to have a small thickness without sacrificing the prescribed mechanical resistance By giving to the opposite side walls 12 a and 12 b the shape of vertical walls and by ensuring that a central element or core 16 a ′ of vertical wall extends to these opposite vertical wall parts as in the illustrated embodiment in Figure 14, one can obtain a butt reinforcement having an extremely high mechanical strength. FIG. 15 shows a safety shoe which uses the toe reinforcement 10 of the embodiment produced as described above and represented in the figure or FIG. 14 This toe reinforcement is fixed between an upper arrow 21 and a lining 22 of the toe of the safety shoe and the skirt part 13 is disposed between the insole 23 and an intermediate sole

  24 Reference 25 designates an outsole.

  It goes without saying that the foregoing description has not been

  given only by way of illustration and not limitation and that variants or modifications can be made to the embodiment described without leaving for

  as much of the scope of the present invention.

Claims (4)

  1 shoe end reinforcement (10), formed of a plastic material reinforced with fibers and comprising: a skirt part (13), bent inwards from the lower parts of a front end part (llb), and opposite side parts (12 a, 12 b), characterized in that the skirt part (13) has a width which decreases progressively in a direction going from the front end towards the rear end of this skirt part and the peripheral edge interior (14) of the skirt part (13) a an arched shape.   2 butt reinforcement according to claim 1, characterized in that the width of the skirt part (13 ') increases in the direction from the end part   front (llb) to the little toe side.   3 butt reinforcement according to claim 1 or 2, characterized in that a vertical wall part (16) provided with a central element or core (16 a) of vertical wall is formed at least in the front end part (llb) of said reinforcement, a connecting part (18) between the front end part (11b) and the skirt part (13) has an arcuate shape such that the inner surface and the outer surface of the arch both have radii of curvature ( R 1 and R 2) relatively large, and the lower end of the central element or core (16 a) of vertical wall reaches the lower surface (17) of the part skirt (13).   4 butt reinforcement according to claim 3, characterized in that the vertical wall part (16) is provided with a central element or core (16 a ') extending from the front end part (llb) to the parts opposite sides (12 a, 12 b).   End reinforcement according to any one of   claims 1 to 4, characterized in that it is formed   of a reinforced plastic material in which relatively long fibers are incorporated, such as carbon fibers and glass fibers. 6 Safety shoe characterized in that it is manufactured by using the toe reinforcement   (10) according to any one of claims 1 to 5.