GB2037569A - Footwear soling - Google Patents

Abstract

A sole unit 11, which is flexed through angle alpha of 50 DEG to 54 DEG when the wearer of the shoe is walking, is pre-shaped with an initial upward curvature of half the angle alpha at the toe. When the sole unit is assembled to the upper 10 by stitching at 12 the sole unit is pressed flat, compressing the part in contact with the ground. In use the initial flexing relieves this stress and the eventual stretching of the bottom of the sole is half that in a conventional shoe. Where the making last has a toe spring (not shown) the initial curvature is greater by half the toe spring. <IMAGE>

Description

SPECIFICATION Footwear soling The present invention relates to soles of footwear.

Such soles are subject to repeated flexing during wear which may result in cracking or splitting of the sole before it has worn down. Traditionally the choice of materials and of the thicknesses in which they are used has been such as to minimize the risk of cracking. However with the use of new materials and the demand forthicker soles, especially in connection with moulded sole units, the problem of cracking is again in evidence.

In accordance with the invention the problem is overcome by providing footwear with a pre-shaped sole which curved upwards towards the toe before assembly and in the finished shoe is held in a prestressed condition with the lower surface of the sole under compression.

Initial flexure of the sole now relieves the prestress in the sole and only the later stages offlexure create tension in the lower surface of the sole. The riskofcracking is thus much reduced. Moreoverthe compression of the lower surface when not flexed makes it more resilienttowear.

The sole may cover only the fore-part of the footwear, which is the area primarily subject to flexure.

This is known as a half-sole but the invention is also applicable to a three-quarter sole or a through sole and more especially to a moulded sole unit which incorporates the heel and forms the whole of the bottom of the footwear.

The invention will be described in more detail with the aid of examples illustrated in the accompanying drawings, in which: Fig. 1 is a side elevation of a shoe with a moulded base unit, shown undergoing flexure during wear, Fig. 2 is a side elevation of the upper and lower parts of the shoe of Fig. 1 during assembly, Fig. 3 is a side elevation of a moulded sole unit for the shoe of Figs. 1 and 2, Fig. 4 is a view similar two Fig. 2 of another form of shoe, Fig. 5 is a side elevation of the moulded sole unit for the shoe of Fig. 4, and Fig. 6 is a side elevation of a sole for a third form of shoe in accordance with the invention, with other parts of the base of the shoe shown in broken lines.

Referring first to Fig. 1 this shows a shoe with an upper 10 and a moulded wedge sole unit 11. The upper 10 is stitched or bonded to the sole unit around a projecting seam or veldt 12. The sole unit 11 has an instep region 13 and above this is the region known as the waist 14 of the shoe. When the shoe is being worn it is constantly being flexed or bent in the joint region which lies between the waist 14 and the toe of the shoe. As shown this results in bending of the sole unit through an angle a which has a maximum value of about 50 to 54 . Especially with a thick moulded sole unit of the type shown, which may be, for example, one inch (25 mm) thick, this results in stretching of the lower surface and compression of the upper surface of the sole unit which may lead to cracking when repeated many times.

To reduce the risk of cracking it is proposed to use a pre-shaped sole unit 11 as shown in Fig. 3 in which the forward part 15 is curved or bent upwards at an angle p which is approximately half the maximum value of angle a, through which the sole is bent when in use. This shaped sole unit is then flattened out during assembly with the upper 10, as shown in Fig. 2. This is effected by pressing the sole unit against the last. On completion of the seam 12 the upper 10 together with an inner sole will hold the sole unit 11 in the flattened condition. The sole unit is thus pre-stressed, its lower surface being under compression and the upper surface under tension.

As the sole unit is flexed during use the pre-stress is relieved over the first 270 offlexure. Thereafter the lower surface comes under tension and the upper surface under compression but the maximum stress is only half that to which a normal moulded unit would be subject. Furthermore as the shoe strikes the ground it is in an unflexed or only slightly bent condition, with the lower surface under compression, and consequently its resistance to wear by abrasion is greater.

As shown in Fig. 4 it is usual when making a shoe with thicker or less flexible soling to use a making last with toe spring, that is to say with the toe bent or curved upwards through the angle y which may be, for example, 100. The angle a through which the sole unit is bent in use is thereby reduced by this amount.

The angle p' shown in Fig. 5 can then be reduced to half the residual angle, that is to say about 20 to 22", the total curvature of the sole before assembly being thus increased by half the toe spring to between 30 and 32".

Figs. 4 and 5 show an upper 20 and a moulded bottom unit 21 which includes a heel 22 and a forepart or toe region 23 which is initially shaped to extend upwards as shown in Fig. 5. Fig. 6, by contrast, shows a half-sole 25 which is shaped to incline upwards towards the toe and which during assembly with an upper (not shown), a through sole 26, and a heel unit 27 is flattened and prestressed as previously described.

1. Footwear having a pre-shaped sole which curved upwards towards the toe before assembly and in the finished footwear is held in a pre-stressed condition with the lower surface of the sole under compression.

2. Footwear as claimed in claim 1 in which the sole is part of a moulded sole unit which forms the whole of the bottom of the footwear.

3. Footwear as claimed in claim 1 or 2 in which the sole is curved upwards towards the toe in the finished footwear but by a smaller angle than before assembly.

4. Footwear as claimed in any of claims 1 to 3 in which the curvature of the sole before assembly is through an angle of 20 to 27".

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Footwear soling The present invention relates to soles of footwear. Such soles are subject to repeated flexing during wear which may result in cracking or splitting of the sole before it has worn down. Traditionally the choice of materials and of the thicknesses in which they are used has been such as to minimize the risk of cracking. However with the use of new materials and the demand forthicker soles, especially in connection with moulded sole units, the problem of cracking is again in evidence. In accordance with the invention the problem is overcome by providing footwear with a pre-shaped sole which curved upwards towards the toe before assembly and in the finished shoe is held in a prestressed condition with the lower surface of the sole under compression. Initial flexure of the sole now relieves the prestress in the sole and only the later stages offlexure create tension in the lower surface of the sole. The riskofcracking is thus much reduced. Moreoverthe compression of the lower surface when not flexed makes it more resilienttowear. The sole may cover only the fore-part of the footwear, which is the area primarily subject to flexure. This is known as a half-sole but the invention is also applicable to a three-quarter sole or a through sole and more especially to a moulded sole unit which incorporates the heel and forms the whole of the bottom of the footwear. The invention will be described in more detail with the aid of examples illustrated in the accompanying drawings, in which: Fig. 1 is a side elevation of a shoe with a moulded base unit, shown undergoing flexure during wear, Fig. 2 is a side elevation of the upper and lower parts of the shoe of Fig. 1 during assembly, Fig. 3 is a side elevation of a moulded sole unit for the shoe of Figs. 1 and 2, Fig. 4 is a view similar two Fig. 2 of another form of shoe, Fig. 5 is a side elevation of the moulded sole unit for the shoe of Fig. 4, and Fig. 6 is a side elevation of a sole for a third form of shoe in accordance with the invention, with other parts of the base of the shoe shown in broken lines. Referring first to Fig. 1 this shows a shoe with an upper 10 and a moulded wedge sole unit 11. The upper 10 is stitched or bonded to the sole unit around a projecting seam or veldt 12. The sole unit 11 has an instep region 13 and above this is the region known as the waist 14 of the shoe. When the shoe is being worn it is constantly being flexed or bent in the joint region which lies between the waist 14 and the toe of the shoe. As shown this results in bending of the sole unit through an angle a which has a maximum value of about 50 to 54 . Especially with a thick moulded sole unit of the type shown, which may be, for example, one inch (25 mm) thick, this results in stretching of the lower surface and compression of the upper surface of the sole unit which may lead to cracking when repeated many times. To reduce the risk of cracking it is proposed to use a pre-shaped sole unit 11 as shown in Fig. 3 in which the forward part 15 is curved or bent upwards at an angle p which is approximately half the maximum value of angle a, through which the sole is bent when in use. This shaped sole unit is then flattened out during assembly with the upper 10, as shown in Fig. 2. This is effected by pressing the sole unit against the last. On completion of the seam 12 the upper 10 together with an inner sole will hold the sole unit 11 in the flattened condition. The sole unit is thus pre-stressed, its lower surface being under compression and the upper surface under tension. As the sole unit is flexed during use the pre-stress is relieved over the first 270 offlexure. Thereafter the lower surface comes under tension and the upper surface under compression but the maximum stress is only half that to which a normal moulded unit would be subject. Furthermore as the shoe strikes the ground it is in an unflexed or only slightly bent condition, with the lower surface under compression, and consequently its resistance to wear by abrasion is greater. As shown in Fig. 4 it is usual when making a shoe with thicker or less flexible soling to use a making last with toe spring, that is to say with the toe bent or curved upwards through the angle y which may be, for example, 100. The angle a through which the sole unit is bent in use is thereby reduced by this amount. The angle p' shown in Fig. 5 can then be reduced to half the residual angle, that is to say about 20 to 22", the total curvature of the sole before assembly being thus increased by half the toe spring to between 30 and 32". Figs. 4 and 5 show an upper 20 and a moulded bottom unit 21 which includes a heel 22 and a forepart or toe region 23 which is initially shaped to extend upwards as shown in Fig. 5. Fig. 6, by contrast, shows a half-sole 25 which is shaped to incline upwards towards the toe and which during assembly with an upper (not shown), a through sole 26, and a heel unit 27 is flattened and prestressed as previously described. CLAIMS

1. Footwear having a pre-shaped sole which curved upwards towards the toe before assembly and in the finished footwear is held in a pre-stressed condition with the lower surface of the sole under compression.

2. Footwear as claimed in claim 1 in which the sole is part of a moulded sole unit which forms the whole of the bottom of the footwear.

3. Footwear as claimed in claim 1 or 2 in which the sole is curved upwards towards the toe in the finished footwear but by a smaller angle than before assembly.

4. Footwear as claimed in any of claims 1 to 3 in which the curvature of the sole before assembly is through an angle of 20 to 27".