Method for the production of cushioned-sole shoes and last to perform the method
United States Patent 3913160

A process for the production of cushioned-sole shoes. An upper is secured to a last having downward projections, the last and upper combination are inserted into a sole mold and the sole is then molded directly to the upper. The sole mold may also include means to form a heel cap integrally with the outsole. A last for use in the above process is also disclosed.

Application Number:
Publication Date:
Filing Date:
Primary Class:
International Classes:
A43B5/04; B29D35/06; (IPC1-7): A43D9/00
Field of Search:
12/142R,142RS,146R,133R,133B 36
View Patent Images:
US Patent References:
2826832Tread member for a shoe1958-03-18Rollman et al.

Primary Examiner:
Lawson, Patrick D.
Attorney, Agent or Firm:
Weingarten, Maxham & Schurgin
What is claimed is

1. A method for the production of a shoe, especially a cushioned-sole shoe, comprising the steps of:

2. The method of claim 1 and further comprising the steps of securing a full length insole within the shoe over the inserted cushion piece and intermediate insole.


This invention relates to a method for the production of shoes, especially cushioned-sole shoes, and more particularly to such a method in which an upper is tacked by means of the conventional thread tacking method onto a last having a downward extension in the ball region. The last together with the upper, which in the region of the last's extension has no insole, is inserted as an upper seal into a sole mold and the outsole member is molded directly on in this mold.


Shoes with cushioned soles have, between the actual abrasion-proof outsole and the insole and at least in the ball part, a soft cushion insert which can consist, for example, of a highly elastic light foam. Such shoes are distinguished by extremely good supporting characteristics.

In known methods for producing such cushioned-sole shoes, the upper is tacked over a standard last, then the cushion piece is applied to the tacked-in insole and the prefabricated outsole is fastened to the upper in a separate procedure by gluing, heat-sealing or vulcanizing.

Glue bonds are particularly suitable for light footwear. However, for heavy work footwear this type of fastening fails in many instances, since the glue film usually is neither oil-resistant nor heat-resistant. The heat-sealed fastening does provide a good resistance of the heat-seal seam to oil, but it can only be used to heat-seal thermoplastic sole materials which in turn are not sufficiently heat-resistant. Direct vulcanization of the outsole to the upper is a widely-used reliable fastening method which also satisfies special requirements. However, with cushioned-sole shoes vulcanization can be applied only if the cushion piece is made of a very compression-resistant, temperature-resistant and therefore very expensive material, e.g., silicone foam rubber, whose structure is not altered during the vulcanization process. The high cost of such material has heretofore effectively prevented work shoes with cushioned soles from being produced by the direct vulcanization method.

In another known process for the production of shoes whose outsole is built as a hollow sole which is subdivided into a multiplicity of air chambers by webs attached to the outsole material, the upper or its lower part forms a one-piece member with the outsole, in whose ball region a soft elastic cushion piece can be inserted. Such shoes have no insole, since the sole chambers have the task of becoming active as an air pump at each step and accordingly must not be tightly and rigidly covered over.

Also known is a process (German Offenlegungsschrift 2,209,870) in which use is made of a last having a movable insert piece which projects over the last's bottom when the upper is placed on the last and forms a catch for a pull-cord bound into the rim of the upper. The cavity formed in the sold member by this insert piece can be filled by a prepared insert. However, this process makes use of a known strip-formed shoe frame which simultaneously represents the sole edge and must be sewn on in a special procedure.


The primary object of the invention is to provide a method of the initially mentioned type by which cushion soles with a joint piece and a heel filler piece can be produced integrally by a molding method and joined directly to the upper without any detrimental effect occurring on the soft-elastic cushion insert or on the joint piece.

In the method according to the invention, a last is used which, at least in the ball portion, has an extension projecting from its underside. An upper, which at least in the region of the last's downward extension has no insole, is tacked onto this last by the conventional thread tacking method. The combination of the last and the upper drawn onto this last is inserted as the upper seal in a mold which is used to vulcanize onto the upper an outsole member made of rubber, to inject a thermoplastic outsole or to foam-in-place an outsole, e.g., made of polyurethane foam. After completely filling the sole cavity formed in the mold and after unmolding and removing the shoe sole from the last, there results a cavity which is open into the shoe's interior. According to the invention, a ball cushion insert made of a soft-elastic light foam is laid into this cavity, preferably provided in the ball region, and an insole may be glued on thereover.

All the listed problems and difficulties are solved by inserting the cushion insert into the sole space, accessible from the shoe's interior, after producing a rigid connection between sole and upper. The most reliable method of fastening the sole and upper, i.e., direct vulcanization, can be chosen without the cushion material being destroyed by pressure and heat. For the actual vulcanization process there results the additional advantage that heat can also be delivered to the sole member from the inside via the last's downward extension, whereby the vulcanization times are considerably shortened. The same holds for the injection molding of thermoplastic soles onto the upper, where the cooling times are shortened by the possibility of an additional internal cooling via the last's downward extension. In the foaming-in-place process of reaction foam soles, there results a faster temper-hardening by tempering the foam mass via the last and the inner last downward extension.

In order to fully exploit the shorter vulcanizing, cooling or temper-hardening times of the process according to the invention, a last used according to the invention can have, besides the extension under the ball part, additional extensions under the joint and heel parts which in the sole member form several cavities which are subdivided by webs and which then are tightly sealed by the inserted insole.

Depending on the particular application of the footwear, the extensions of the last used to perform the process according to the invention can be perfected. For example, in order to achieve a special elasticity of the sole, the last's extension can have a downward-broadened cross-section which results in an outsole with upwardly reinforced rims and causes the elastic cushion piece of the ball to grip under the tacking rim of the leg. To facilitate removal from the last, the back of the front extension can also be sloped.

For especially heavy work shoes with reinforced heel part, it may be appropriate to produce the upper tacked in the ball part without an insole and to tack in the joint and heel parts with a sewn-in intermediate insole of the California type, with a joint piece and a heel filler piece being fastened beneath this rear intermediate insole. After molding the outsole onto the thus improved upper, the cushion insert is laid into the front cavity from the shoe's interior and a complete insole is glued on. The preferably utilized thread tacking method and the California manufacturing method are particularly simple to perform if no back and front caps have to be worked into the upper. To be able to produce a sturdy shoe nevertheless, the sole material can advantageously be drawn up externally at the upper as a cap reinforcement, so that no reinforcing caps have to be worked into the upper.


The objects, advantages and features of the invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawing in which:

FIG. 1 shows a shoe produced by the process according to the invention, in a partially sectioned side view;

FIG. 2 shows the shoe of FIG. 1 with a differently shaped cushion insert, in a partially sectioned perspective view;

FIG. 3 shows a cross-section through a sole mold with inserted last and upper; and

FIG. 4 shows the last used to perform the process, in a partially sectioned perspective view.


The shoe depicted in FIGS. 1 and 2 consists of an upper 3 thread-tacked at 4, to which an outsole 6 is directly molded. Worked into the outsole member may be one or more cavities, one of which in the ball region is filled by a cushion insert 7 made of a soft-elastic material, in the joint region by a joint piece 14 and in the heel region by a heel filler piece 15. Above the joint piece 14 there is an intermediate insole 12 which is sewn into the upper at 13 by the California method. The joint piece 14 and the heel filler piece 15 are fastened to the intermediate insole 12 in the usual manner prior to the molding of the outsole member 6, whereas the cushion piece 7 filling the cavity in the ball region is inserted from the shoe's interior only after the outsole has been formed. An insole 8 extends over the entire sole region and is either loosely laid in or tightly glued to the sole.

To improve the supporting characteristics, the cavity forming the receiving space for the cushion insert can be so constructed by appropriate shaping of the last's extension that the cushion insert extends down to below the tacking seams, so that the cushion piece in the ball part of the shoe extends over the full width of the insole. This is depicted by undercut 16 below the tacking seams and located at the front and side rims.

To achieve a greater sturdiness of the shoe, the outsole material in the illustrated embodiment may be drawn up in the heel region to a heel cap 17 at the upper. A front cap can be molded on in the same manner, into which can be incorporated a rigid insert made of steel, for example.

The shoe shown in FIG. 2 differs essentially only in a construction of the ball cushion different from that of FIG. 1. This ball cushion has a rectangular cross-section by which the front and side rims of the outsole become stronger.

FIG. 3 shows the arrangement of an upper 3 tacked onto a last 1 according to the invention, and inserted in a last mold 5 which consists of side parts 5a and a bottom stamp 5b and in which there is a pouring opening 5c to introduce the sole material into the cavity 18. This figure also shows the special cross-section of the last's extension 2.

The last shown in FIG. 4 has an extension 2 in the ball region, whose lateral edges are vertical to produce a shoe as in FIG. 2. The back edge 11 of this extension 2 is sloped in order to facilitate the removal of the finished shoe from the last. In the joint region and in the heel part there are shown optional additional extensions 9 which are separated from each other by transverse fissures 10. These extensions serve to form cavities in the corresponding regions, which, after forming the outsole member, are then covered by an insole which is glued onto the webs of sole material corresponding to the fissures 10 or, in the event that the insole is inserted loosely, is supported against them.