DE102020121560A1 - Method of making a last - Google Patents

Abstract

The invention relates to a method for producing a last (10), with the steps: (a) detecting a target outer contour of the last (10), (b) 3D printing of printing material, in particular plastic, so that at least one final contour piece (14) is formed, and (c) connecting the end contour piece (14) to a strip core (12) so that the strip (10) is formed, (d) the at least one end contour piece (14) surrounding the strip core (12).

Description

The invention relates to a method for producing a last. According to a second aspect, the invention relates to a last.

The last is the most important production tool in shoe manufacture. The last serves both as a mold for forming the upper of the shoe and as a support for further production steps such as sewing, gluing and trimming. Lasts made of plastic or wood are often used in the mass production of shoes.

When shoes are made to measure, an individual last is made for each customer. As a rule, such a last consists of wood and must be individually manufactured for the later wearer of the shoe. This can be done, for example, by machining. The disadvantage of this is the comparatively high cost of manufacturing the last.

The object of the invention is to improve the production of lasts for individual shoe production.

The invention solves the problem with a method for producing a last with the steps of (a) detecting a target outer contour of the last, (b) 3D printing of printing material, in particular plastic, so that at least one end contour piece is created, and (c) connecting the Final contour piece with a strip core, so that the strip is formed which has the target outer contour, wherein (d) the at least one final contour piece surrounds the strip core.

According to a second aspect, the invention solves the problem with a last that has a last core and at least one end contour piece, the end contour piece being connected to the last core, in particular detachably, in such a way that the at least one end contour piece surrounds the last core.

The advantage of the invention is that the strip core can be used for a large number of strips. In other words, the last core is recyclable. Only the at least one end contour piece has to be produced individually for each wearer of the shoe. This reduces resource consumption.

It is also advantageous that such a last can generally be produced faster than the production of a last, for example by machining from a blank.

It is also advantageous that the production of a last can often be accomplished more quickly than before by means of the invention. This facilitates the mass production of individually fitted shoes.

It can also be advantageous that the production of the final contour pieces can take place at a different location than the production of the last and/or the shoe. In this case it is only necessary to bring the end contour pieces from the place of manufacture to the place of manufacture of the shoes. There the at least one end contour piece can then be connected to the strip core. The location at which the final contour pieces are manufactured is preferably at a distance of at least 10 km, in particular 100 km, from the location at which the shoes are manufactured using the finished last.

In the context of the present description, the detection of the target outer contour is understood in particular as a process in which data that encode the target outer contour is transmitted to a 3D printing device. In other words, it is in particular a detection of the desired outer contour by the 3D printing device. The method preferably includes the step of recording form data of a foot of a subsequent wearer of the shoe, which is manufactured with the last. The target outer contour is calculated from this shape data. This can be done, for example, using a CAD system.

3D printing is understood to mean in particular the construction of the final contour piece from a raw material. The term 3D printing is used synonymously with the term additive manufacturing. In particular, 3D printing involves building up the final contour piece layer by layer.

It is possible and preferred, but not necessary, for the bar core to be solid. It is also possible, but not necessary, for the strip core to also be made of plastic. It is also possible for the strip core to consist of metal, for example, or to be constructed from two or more materials.

According to a preferred embodiment, the strip is a folding strip.

A plastic is preferably used as the printing material. For example, the plastic is a polylactide (PLA). Alternatively or additionally, the plastic can be an acrylonitrile butadiene styrene copolymer (ABS). Alternatively or additionally, the plastic can be high-density polyethylene (HDPE). It is also possible that the printing material is a plastic mixture and contains two, three or more plastics.

According to a preferred embodiment, the last core has a front shoe core element and a heel core element, which can be moved relative to one another and complement one another to form the last core. After the shoe has been manufactured, the last must be removed from the finished shoe. The last is therefore designed to be removable from the finished shoe. This can be done, for example, in that the front shoe core element and the heel core element are mounted pivotably on one another. Alternatively, the forefoot core member and the heel core member may be connected and disconnected by translational motion.

The final contour piece preferably has at least one front shoe piece which is designed in such a way that the front shoe core element can be brought into the front shoe piece without play. According to a method according to the invention, the front shoe core element is connected to the front shoe piece without play, for example the front shoe core element is inserted or introduced into the front shoe piece.

The end contour piece preferably has at least one heel piece which is designed in such a way that the heel core element can be connected to the heel piece without play. According to a preferred embodiment of the method, the heel core element is connected to the heel piece without play, for example by inserting the heel core element into the heel piece.

It is particularly favorable if the final contour piece has two, in particular exactly two, front shoe pieces which can be connected to one another along a connecting line, the connecting line running in the longitudinal direction of the last. The two forefoot pieces can then be connected to the core forefoot member by being attached to the forefoot piece from respective opposite sides of the forefoot piece. It is favorable if the two front shoe pieces are connected to each other or to the front shoe piece, for example by screwing, gluing or clipping. Clipping means connecting by means of a snap connection.

It is also favorable if the end contour piece has two, in particular exactly two, heel pieces. These heel pieces can preferably be connected to one another along a second connecting line which runs in the longitudinal direction of the last. Preferably, the heel pieces, like the front shoe pieces, can each be connected from the side at the end contour piece.

In other words, it is favorable if the end contour piece has four, in particular exactly four, parts.

According to a preferred embodiment, the final contour piece forms a, preferably closed, shell around a sole area of the last core and/or an instep area 30 of the last core. In particular, the front shoe pieces and the heel pieces form the shell around the sole area and/or the instep area of the last core.

The end contour piece preferably forms an, in particular closed, sleeve around a forefoot area of the last core. Alternatively or additionally, the end contour piece preferably forms a, in particular closed, shell around a heel area of the last core. In particular, the front shoe pieces form the shell around the forefoot area of the last core. Preferably, the heel pieces form the wrap around the heel area

The feature that the final contour piece, in particular the at least one front shoe piece and/or the at least one heel piece forms a shell around the respective area, means in particular the corresponding piece, i.e. the final contour piece, the at least one front shoe piece or the at least one heel piece , forms a container that can hold balls with a diameter of 2 millimeters.

It is favorable if the surface of the strip core consists predominantly, in particular exclusively, of flat three, four, five and/or six corners in terms of area. It has been found that such a strip core ensures a particularly high degree of security against twisting of the end contour piece relative to the strip core.

According to a preferred embodiment, the final contour piece is bordered by flat surfaces in the areas in which it bears against the front shoe piece or the heel piece. Preferably, these flat surfaces correspond to the flat surfaces of the surface of the strip core. For example, the flat surfaces are polygons, in particular triangles, quadrilaterals, pentagons and/or hexagons. It is also possible that the surface has different polygons.

The detection of the desired outer contour preferably has the following steps (a) scanning of the foot, in particular detection of a foot by means of a camera, so that foot shape data are obtained and (b) calculating the target outer contour from the foot shape data. The desired outer contour is then preferably transmitted to a 3D printer. The foot can be scanned using a camera. It is favorable if this camera is the camera of a mobile phone.

Alternatively, the target outer contour can be determined, for example, by manually measuring the foot dimensions, for example using a measuring tape. Again alternatively, the target outer contour can be modeled manually in a CAD model, for example.

The method preferably includes the step of calculating an inner contour of the final contour piece from a main body outer contour of the last core. The outer contour of the base body is stored, for example, in a digital memory. For example, the inner contour can be calculated using a CAD program.

It is favorable if the method has the following steps: (a) calculating a volume difference between the target outer contour and a first last core and at least one second last core that differs from the first last core, and (b) 3D printing of the final contour piece, that matches the last core with the smallest volume difference.

In the case of the individual production of shoes, shoes of different sizes are produced in an approximately random manner. In order to keep the volume that has to be produced by means of 3D printing as small as possible, it is advisable to keep several last cores in stock and to use the last core for which the smallest volume of printing material has to be used to produce the last.

The volume difference is preferably calculated under boundary conditions. For example, a boundary condition can be that a minimum material thickness of the final contour piece is above a predetermined minimum thickness. The predetermined minimum thickness can be at least one millimeter, for example, in particular at least 1.5 millimeters. The predetermined minimum thickness is preferably less than 5 millimeters, in particular less than 4 millimeters.

Alternatively or additionally, a boundary condition can be that the respective last core must be available for the production of the last. If, for example, all the bar cores are used at the time of calculation, then according to a preferred embodiment it is provided that these bar cores are not used for the calculation of the volume difference.

According to the invention is also a method for manufacturing a shoe with the steps (a) manufacturing a last using a method described above, (b) manufacturing the shoe by means of the last and (c) separating the core of the last from the final contour piece. In particular, the core of the last is subsequently used to produce a further last. It is possible that the final contour piece will be discarded after the shoe has been manufactured. In particular, it is possible to materially recycle the end contour piece. A printing material blank is preferably produced from the final contour piece. For example, if the 3D printing is fuse deposition modeling or fused-filament fabrication, where the substrate is plastic, which is supplied in the form of a rod-like substrate blank, this substrate blank can be removed from the final contour piece are produced.

The final contour piece preferably has at least one front shoe piece, in particular two, for example exactly two, front shoe pieces. (b) the last core has a front shoe core element and the front shoe core element is arranged without play in at least one front shoe piece.

Alternatively or additionally, the end contour piece preferably has at least one heel piece and the last core has a heel core element. The heel core element is then preferably arranged without play in at least one heel piece.

It is favorable if the final contour piece is predominantly bordered by flat surfaces, at least in terms of surface area, in the areas in which it bears against at least one front shoe piece and/or at least one heel piece. The feature that its surface area is predominantly bordered by flat surfaces means, in particular, that the surface is made up of at least 50% flat surfaces. In particular, the flat surfaces are polygonal surfaces, in particular triangular, quadrilateral, pentagonal or hexagonal surfaces. Triangular and/or square surfaces are particularly favorable.

The at least one front shoe piece and the at least one heel piece are preferably connected in a form-fitting manner to the last core. In particular, the front shoe piece and the at least one heel piece are connected to the last core by means of a connecting element, in particular a screw or a pin, or a snap connection.

• 1a eine Seitenansicht eines Leistens mit dem Leistenkern und einem Endkonturstück, von dem eine Hälfte entfernt ist,
• 1 b eine Ansicht eines Fersenstücks des Leistens gemäß 1a,
• 1c eine Ansicht auf ein Vorderschuhstück des Leistens gemäß 1a und
• 2 eine Explosionszeichnung eines erfindungsgemäßen Leistens.

The invention is explained in more detail below with reference to the attached drawings. while showing

• 1a a side view of a last with the last core and a final contour piece, half of which has been removed,
• 1 b a view of a heel piece of the last according to FIG 1a ,
• 1c a view of a front shoe piece according to the last 1a and
• 2 an exploded drawing of a last according to the invention.

1a shows a last 10 which has a last core 12 and an end contour piece 14 . The last core 12 has a front shoe core element 16 and a heel core element 18. The two core elements 16, 18 are pivotally connected to one another by means of a coupling structure 20, which in the present case is designed as a pivot joint. In other words, the heel core element 18 can be pivoted relative to the front shoe core element 16 as indicated by an arrow P.

The end contour piece 14 has a first front shoe piece 22.1 and a second front shoe piece 22.2 (cf. 1c ). The end contour piece 14 also has a first heel piece 24.1 and a second heel piece 24.2 (cf. 1b) .

1 b and 1c show that support material 36 can be printed out with 3D printing. This is removed in a further work step in order to obtain the final front shoe piece 22.1. Depending on the 3D printing method, however, it is not necessary for support material 36 to be printed out by 3D printing.

The front shoe pieces 22.1, 22.2 rest against one another at a contact surface _K22 . The heel pieces 24.1, 24.2 are also in contact with one another along a contact surface _K24 . In addition, the front shoe pieces 22.1, 22.2 and the heel pieces 24.1, 24.2 are in contact with one another in a third contact surface K _{22, 24} . The front shoe pieces 22.1, 22.2 and the heel pieces 24.1, 24.2 thus form the final contour piece 14. In the present embodiment, they form a closed shell around a sole area 28 of the last core 12 and an instep area 30 of the last core 12.

In the present embodiment, the end contour piece 14 forms a shell around a forefoot region 29 of the last core 12. In the present embodiment, the end contour piece 14 also forms a shell around a heel region 31 of the last core 12.

1a shows that the end contour piece 14 can have recesses 26.1, 26.2. A mounting element 32.1 or 32.2 shown schematically, for example in the form of a screw, can be pushed through the recesses 26.1, 26.2 in order to connect the respective parts of the end contour piece 14 to one another and/or to the strip core 12. In this case, it is favorable if the front shoe pieces 22.1, 22.2 and the heel pieces 24.1, 24.2 have a depression on their outside to accommodate the head of the respective assembly element 32.1, 32.2, resulting in a smooth surface.

2a shows the strip core 12 in a perspective view. It can be seen that a surface O ₁₂ of the strip core 12 is composed of flat surfaces F ₁ , F ₂ . The flat surfaces are polygonal surfaces, in particular squares and triangles.

2 B shows the front shoe piece 22.2 in a perspective view, wherein the support material 36 can be present in the form of support webs 34.i. In 2 B the state is shown in which they are not yet removed. The supporting webs 34.i (i=1, 2,...) are created when the front shoe piece 22.2 is manufactured by 3D printing. In the present case, the front shoe piece 22.2, like the other parts of the final contour piece 14 (cf. 1 ) produced by melt stratification.

3 shows schematically an exploded view of the last 10 according to the invention with the front shoe pieces 22.1, 22.2, the heel pieces 24.1, 24.2, the front shoe core element 16 and the heel shoe core element 18. It can be seen that the front shoe piece 22.1 and the heel piece 24.1 on the one hand and the On the other hand, the front shoe piece 22.2 and the heel piece 24.2 form a coupling structure which corresponds to the coupling structure 20.

1c shows that the front shoe piece 22 has an inner surface I _22.2 , which is also made up of flat surfaces F _j . Each area of the inside I ₂₂ corresponds to an area F _j of the surface O ₁₂ (cf. 2 ) of the last core 12. If the parts of the end contour piece 14, in particular also the front shoe piece 22.2, are fastened to the last core 12, a stable connection is formed between the last core and the end contour piece. It is favorable if the surface O ₁₂ does not have any undercuts in the area in which the end contour piece 14 bears against it, provided that the corresponding area does not form a snap connection between the strip core 12 and the end contour piece 14 .

The surface O ₁₂ of the bar core 12 has N faces N _i (i=1, 2, ..., N). The number N is preferably at least 5 and at most 5000, in particular at most 3000.

To produce a last 10 according to the invention, the foot of the later wearer of the shoe is first scanned. This can be done, for example, using a camera, for example the camera of a mobile phone. Alternatively, other methods for scanning objects can also be used, for example fringe projection, transit time measurements. Alternatively, it is possible to measure the foot by hand.

The target outer contour is calculated from this data. The target outer contour is understood to be a mathematical description of the surface of the last 10 by discrete points that describe the course of the surface of the last 10, or a parameter representation, for example by NURBS objects. This data is processed, for example, using a CAD program. A geometric model of the final contour is calculated from the target outer contour by subtracting the outer contour of the last core and printed out using a 3D printer. The result is in the 1b , 1c and 2 B to see.

It is possible to subtract the outer contour of the strip core from the target outer contour not only for the first strip core 12.1, but also for a second strip core, which differs from the first strip core. The volume difference is then calculated in each case, i.e. the volume of the respective final contour piece, and the last core with the smallest volume difference is used to manufacture the last.

Reference List

10

Afford

12

inguinal core

14

final contour piece

16

Front shoe core element

18

Heel shoe core element

20

coupling structure

22

front shoe piece

24

heel piece

26

recess

28

sole area

29

forefoot area

30

clamping range

31

heel area

32

mounting element

34

support bar

36

support material

fj

flat surface

I22

Inner surface of the forefoot piece

i, j

running index

K22

contact surface

K24

second contact surface

K22,24

third contact surface

N

number of surfaces

O12

surface of the inguinal core

P

arrow

Claims (11)

Method for producing a last (10), with the steps: (a) detecting a target outer contour of the last (10), (b) 3D printing of printing material, in particular plastic, so that at least one final contour piece (14) is created, and (c) connecting the end contour piece (14) to a strip core (12) so that the strip (10) is formed, (d) the at least one end contour piece (14) surrounding the strip core (12). procedure after claim 1 , characterized in that (a) the last core (12) has a front shoe core element (16) and a heel core element (18) which are movable relative to one another and complement each other to form the last core (12), (b) the final contour piece ( 14) has at least one front shoe piece (22), (c) the front shoe core element (16) is connected to the front shoe piece (22) without play, (d) the end contour piece (14) has at least one heel piece (24) and (e) the Heel core element (18) is connected without play to the heel piece (24). Method according to one of the preceding claims, characterized in that the end contour piece (14), in particular the front shoe pieces (22.1, 22.2) and the heel pieces (24.1, 24.2), a preferably closed sleeve around a forefoot area (29) of the last core (12 ) and/or a heel area (31) of the last core (12). Method according to one of the preceding claims, characterized in that the end contour piece (14) in the areas in which it rests against the forefoot piece (22) or the heel piece (24), is bordered by flat surfaces (F _j ). Method according to one of the preceding claims, characterized in that the detection of the target outer contour has the following steps: (a) scanning the foot, in particular detecting a foot by means of a camera, so that foot shape data are obtained, and (b) calculating the target Outer contour from the foot shape data. Method according to one of the preceding claims, characterized by the steps: (a) calculating a volume difference between the target outer contour and a first strip core (12) and at least one second strip core which differs from the first strip core (12), and (b) 3D printing of the final contour piece (14) that fits the last core (12) with the smallest volume difference. Method of making a shoe, comprising the steps (a) producing a last (10) using a method according to any one of the preceding claims, (b) manufacturing the shoe by means of the last (10) and (c) Separating the last core (12) from the final contour piece (14) (and reusing it to produce another last (10)). strips (10), the (a) an inguinal core (12) and (b) has at least one final contour piece (14), (c) the end contour piece (14) being detachably connected to the strip core (12) in such a way that the at least one end contour piece (14) surrounds the strip core (12). Last (10) after claim 8 , characterized in that (a) the end contour piece (14) has a front shoe piece (22), (b) the last core (12) has a front shoe core element (16) and (c) the front shoe core element (16) has no play in at least a front shoe piece (22) is arranged, and/or that (d) the final contour piece (14) has a heel piece (24), (e) the last core (12) has a heel core element (18) and (f) the heel Core element (18) is arranged without play in at least one heel piece (24). Last (10) after claim 8 or 9 , characterized in that the end contour piece (14) is bordered by flat surfaces (F _j ) in the areas in which it bears against the at least one front shoe piece (22) and/or the at least one heel piece (24). Last (10) after one of Claims 8 until 10 , characterized in that the at least one front shoe piece (22) and the at least one heel piece (24) are positively connected to the last core (12).

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