Patent Description:
The fastening between heel and insole in women's shoes is carried out by means of mechanical connecting methods, such as for example the use of one or more screws and/or nails. They take hold in the body of the heel (whether it be made of polymer material or wood or other material) and are inserted from the inner part of the shoe (insole), prior to the application of the insole. A possible defect occurring during fastening may result in a partial detachment of the heel during the regular use of the shoe.

The quality check is commonly performed during the production by a skilled operator who stresses a (randomly selected) shoe by manually bending it. Specifically, the operator grasps the heel with one hand, grasps the opposite (open) side of the shoe with the other hand, and exerts a compression which causes a pressure-flexure stress in the attachment point between heel and insole. Defective fastening results in the partial detachment of the fastening, with the formation of a visible gap (with the naked eye) between insole and heel. This test, which is manually performed, has poor repeatability and objectivity, depending on the force imparted by the operator, which is neither measured nor controlled. Therefore, the assessment of the adequacy of the fastening of the tested shoe is a prerogative of the subjective judgement of the operator.

Both European and American legislations are provided with experimental tests (on whole shoes) for checking the adhesion between heel and insole. Such experimental tests are of a destructive nature, require partially cutting a part of the shoe, and can only be performed in a laboratory. Therefore, they are not suitable for performing a quality check at the customers' home or on production lines without destroying shoes having an adequate fastening degree.

In particular, Standard ASTM F2232-<NUM> is significant for the prior art, prescribing an experimental traction test in which the heel is stressed by a longitudinal force (with respect to the shoe). The shoe is tested in vertical position, with the front part down, grasped by the grip of the testing machine. In order to ensure the proper application of the load, a through hole is made in the heel, in which a transverse bar is inserted, which, through a specific apparatus, is connected to the other end of the testing machine. The test measures the maximum force required to detach the heel from the insole. Although this experimental test is instrumented and repeatable, it is not suitable for the quality check activity which is to be performed: indeed, the traction stress of this test does not cause the partial detachment phenomenon between heel and insole; moreover, by irreparably damaging the heel (with the through hole) and the front part of the shoe (with the grip of the vice, which damages the outer surface of the shoe), the methods of applying the load do not allow non-destructive type tests.

Pendulum devices for assessing the resistance to the impact of high heels in a laboratory, for example described in <CIT> and <CIT>, devices for measuring the performance of shoes in terms of comfort, for example shown in <CIT> and <CIT>, and devices for measuring and simulating the wear of the soles of shoes, for example disclosed in <CIT>, <CIT> and <CIT> are also known.

It is the object of the present invention to provide a device for checking the fastening quality of the heel to the insole of women's shoes with a medium/high heel.

It is a further object of the present invention that said device allows a non-destructive, repeatable and quantitative check on the adequacy of the connection of the heel to the insole.

Again, it is a further object of the present invention that the device is easy to transport and operate, thus allowing an easy movement thereof, when required.

According to the invention, said and further objects are achieved by a device for the quality check of the adhesion between a heel and an insole of a shoe, characterized in that it comprises:.

Not last, it is the object of the present invention to realize a method for the quality check of the adhesion of the heel to the insole which is not destructive, is immediate to assess, and which uses simple and affordable means.

According to the invention, said not last object is achieved by a method for the quality check of the adhesion between a heel and an insole of a shoe, characterized in that it comprises the following steps:.

The device advantageously realizes an experimental procedure for assessing the quality of the fastening between heel and insole through a non-destructive test.

The device is transportable, simple to set up and implements a method for interpreting the results of non-destructive tests and for providing a repeatable and quantitative indication on the adequacy of the connection of the heel to the insole.

The manual test performed by the skilled operator is advantageously repeated with scientific accuracy without breaking the sample subjected to the test by stressing only the connection between heel and insole in order to identify the defective connections which result in apparent gaps or detachments in an early step of the application of the load with respect to the connections having sufficient quality.

These and other features of the present invention will become more apparent from the following detailed description of a practical exemplary embodiment thereof, shown by way of non-limiting example in the accompanying drawings, in which:.

A device <NUM> for the quality check of the adhesion between a heel <NUM> and an insole <NUM> of a shoe <NUM> comprises a frame <NUM> consisting of a base <NUM>, a cover <NUM> and four uprights <NUM> connected to the four vertexes of the base <NUM> and supporting the cover <NUM>. By insole <NUM> it is meant the element on which the user's foot rests.

The base <NUM> preferably consists of a stiff metal plate framed with "L" shaped profiles serving the purpose of increasing the flexing rigidity. The fastening between plate and profiles occurs by means of solid rivets or bolted connections.

The four uprights <NUM> preferably are "L" or "U" shaped profiles.

A loading cell <NUM> with force sensors is fastened in the middle of the base <NUM>: the load application axis (loading axis) of the loading cell <NUM>, which is arranged vertically, is taken as a reference for defining a main axis <NUM> of the device <NUM>.

A support <NUM> for the shoe <NUM> is coupled over the loading cell <NUM>. Such a support <NUM>, which is made of a material which does not damage the finishing of the heel <NUM>, has dimensions which are not greater than those of the base <NUM>, and a seat <NUM> for the heel <NUM> is made on the upper part, preferably a recess, the shape of which substantially is the negative of the heel <NUM>. The shoe <NUM> indeed is arranged vertically (<FIG>), with the back part of the heel <NUM> at the bottom accommodated in the recess of the support <NUM>, which therefore serves the purpose of keeping the correct centering of the heel <NUM> when the test is being performed.

The centering means may be of other type, for example a gripper coupler, but the heel <NUM> associated with the support <NUM> preferably is to be kept centered, laying on the support <NUM> substantially in the longitudinal direction of the height of the heel <NUM>, i.e. at the back associated with the support <NUM>, simply resting on and/or with suitable coupling means.

Even if the heel <NUM> has a curved axis, the support <NUM> preferably is such as to ensure the ideal straight line joining the two back upper and lower ends of the heel <NUM> being parallel to the surface of the base <NUM> of the device <NUM> (compare <FIG>).

Therefore, the heel <NUM> lies at the back on the support <NUM> coupled to the loading cell <NUM>.

In a preferred embodiment, said ideal straight line is geometrically contained in a plane orthogonal to the main axis <NUM> which intersects said ideal straight line in the intermediate point between said two end points of the heel <NUM>.

There is a through hole through which a threaded rod <NUM> may slide, in the middle of the cover <NUM>, at the main axis <NUM> of the device <NUM>. Such a threaded rod <NUM> meshes in a ring nut <NUM> fastened to the cover <NUM> through screws or rivets.

An ergonomic knob <NUM> for manually actuating the device <NUM> is fastened at the upper end of the threaded rod <NUM>. Alternatively, the movement may be obtained by means of a suitable pneumatic, hydraulic or electric actuation system (with linear actuator).

A plate <NUM> is fastened at the lower end of the threaded rod <NUM>, being able to support a presser <NUM> so that the latter is free to rotate about the main axis <NUM> of the device <NUM>, advancing along said main axis <NUM> due to the ring nut <NUM> fastened to the cover <NUM>. The presser <NUM> preferably has a beveled tip and is covered with soft material which does not damage the insole <NUM> of the shoe <NUM>.

The pressing means may be of another type, for example with lever-actuated means. The use of a threaded rod <NUM> is preferred because it ensures a greater accuracy of the movement without sudden actuations. Contrarily, the lever causes a load application which is too quick, with too great forces involved.

Regardless of the shape of the pressing means, they are to act on the insole <NUM> along the main axis <NUM>, which corresponds to the loading direction (loading axis) which is detectable by the loading cell <NUM>. The support <NUM> is able to counteract the thrust of the pressing means.

The cover <NUM> preferably consists of a metal plate framed with "L" profiles and is provided with longitudinal and transverse stiffeners, which increase the rigidity thereof.

A distance detector <NUM>, preferably an ultrasound detector, is applied below the cover <NUM>, facing the plate <NUM>, so as to measure the position of the presser <NUM> by means of position sensors.

The detection means may be of various type, in any case being able to measure the position of the pressing means with respect to the insole <NUM>.

Operatively, there is an initial need to calibrate the device <NUM> by bringing the presser <NUM> into contact with the insole <NUM> in the shoe <NUM> at the beginning of the test: the force and movement values of the loading cell <NUM> and of the detector <NUM> are zeroed.

The test consists in pushing the presser <NUM> along the main axis <NUM> so as to compress the shoe <NUM> up to reaching a specific given value of the movement for the model of the shoe <NUM> and the heel <NUM>.

The movement and the corresponding force are recorded during the test, thus generating a force-movement diagram FS (<FIG>, F in Newton and S in millimeters). At the end of the test, the shoe <NUM> for which the force-movement diagram FS will not deviate from an envelope area <NUM> defined by sample tests and delimited in <FIG> by two dotted lines, will pass the quality test.

Therefore, the device <NUM> comprises an electronic processor in which there are stored the sample tests of the shoe <NUM> and of the heel <NUM> by model and a processed envelope area <NUM>, namely an area of the force-movement graph FS in which the shoe <NUM> is judged with a positive adhesion between the heel <NUM> and the insole <NUM>.

Alternatively, the check may occur visually in the device <NUM>, the device <NUM> having been however initialized and sample tests having been performed to understand in advance the movement of the presser <NUM> to be set.

In the embodiment described herein, the device <NUM> thus comprises the frame <NUM> for housing the shoe <NUM>, the presser <NUM> and the related actuation system (whether it is manual, hydraulic or pneumatic), force and movement sensors, a wired connection with an electronic processor, and possibly a software for comparing data from the test and those from the (conveniently prepared) database which determines if the sample passes the quality test or not.

In particular, the height of the heel <NUM> is the main parameter regulating the mechanical behavior of the shoe <NUM>. The same trend in the force-to-movement ratio corresponds to each height of the heel <NUM> (excluding the defective samples). Vice versa, the heels <NUM> having a defect (which therefore may undergo early detachment) show force-movement diagrams which are significantly different from those of the non-defective models. By way of example, refer to the comparison in <FIG> between the experimental test on a ready-to-use model and on a defective one, in which a diagram <NUM> representing a shoe <NUM> with a positive adhesion of the heel <NUM> to the insole <NUM> is depicted, and a diagram <NUM> representing a shoe <NUM> with a defective adhesion of the heel <NUM> to the insole <NUM> is depicted.

As already mentioned, once a significant number of sample tests is performed for the different models of heel <NUM> and of shoe <NUM> (including the various possible heights), an area of peculiar envelope <NUM> of force-movement curves FS associated on a statistical base with each type of heel <NUM> and shoe <NUM> may be outlined. Thus, a given connection between heel <NUM> and insole <NUM> will be defective if the force-movement diagram FS of the corresponding experimental test falls outside the reference envelope area <NUM>.

The frame <NUM> is made of aluminum or other lightweight and resistant material.

In the above-described embodiment particularly shown in <FIG> and <FIG>, the main axis <NUM> is vertical and the heel <NUM> lies longitudinally substantially on a horizontal plane. Said embodiment facilitates the centering of the heel <NUM> by the seat <NUM>, but a different lying position of the shoe <NUM> and of the pressing means is possible: for example, the support <NUM> may comprise coupling means which allow the heel <NUM> to be held longitudinally vertical, namely with the shoe <NUM> horizontal as worn by the user; accordingly, the pressing means are able of moving along a horizontal main axis <NUM> while always acting on the insole <NUM> in the shoe <NUM>.

Regardless of the lying position of the shoe, the device <NUM> advantageously realizes an experimental procedure for assessing the quality of the fastening between heel <NUM> and insole <NUM> through a non-destructive test.

The device <NUM> is transportable, simple to set up and implements a method for interpreting the results of non-destructive tests and for providing a repeatable and quantitative indication on the adequacy of the connection of the heel <NUM> to the insole <NUM>.

Claim 1:
Device (<NUM>) for the quality check of the adhesion between a heel (<NUM>) and an insole (<NUM>) of a shoe (<NUM>), characterized in that it comprises
a support (<NUM>) for the shoe (<NUM>) so that the heel (<NUM>) is posteriorly associated with the support (<NUM>),
a loading cell (<NUM>) to which the support (<NUM>) is coupled,
pressing means able to interact with the insole (<NUM>) along a main axis (<NUM>) coinciding with a loading axis of the loading cell (<NUM>), and
means able to detect the position of the pressing means.