Articulated shoe last for footwear comprising articulation assembly with improved spring

Abstract

The invention relates to an articulated last (A2, B2) for manufacturing a shoe; the articulated last (A2, B2) comprises a front half body (1), a rear half body (2) and an articulation assembly (Ga, Gb) keeping the two half bodies (1, 2) movably connected to each other; wherein the hinge assembly (Ga, Gb) comprises a C-shaped spring (6) comprising an inner wire (7) and an outer coating (8) of plastic material completely covering the inner wire (7).

Description

Technical Field

[0001] This industrial invention patent application relates to an articulated last, comprising an articulated assembly with an improved spring. Background Art

[0002] As we all know, when manufacturing shoes, a tool called a "last" is used, which can replicate the shape of the foot when wearing the shoe according to each shoe size to be produced.

[0003] Such a last accompanies the production of the shoe until the final step of the shoe production process.

[0004] It is known that a one-piece shoe last made of wood or plastic or a composite material can completely replicate the shape of the foot. However, such an one-piece shoe last cannot be used in the case of a particularly narrow upper because once the shoe is made, the shoe last cannot be removed from the shoe.

[0005] Therefore, over time, people invented an articulated shoe last. This patent application is related to such an articulated shoe last.

[0006] The articulated last comprises two halves, a front half and a rear half, which are movably connected by a hinge assembly including a spring that exerts an attractive force between the two halves.

[0007] There are several types of articulated lasts, which differ from each other in particular in the type of hinge assembly that connects the two halves and the manner in which the two halves are allowed to move relative to each other.

[0008] For example, refer to Figure 1 , 1A , 1B, 1C, 2, 2A and 2B describe two conventional articulated shoe lasts A1 and B1 in the prior art, namely a first articulated shoe last A1 and a second articulated shoe last B1.

[0009] The two articulated shoe lasts A1 and B1 each include a front half body 1 and a rear half body 2, which are movably mounted in a first extended position (eg Figure 1 and Figure 2 ) and the second retracted position (as shown Figure 1A and Figure 2A shown).

[0010] The front half body 1 has a rear operating surface 11 facing the rear half body 2 , while the rear half body 2 has a front operating surface 21 facing the front half body 1 .

[0011] The shapes of the rear operating surface 11 of the front half body 1 and the front operating surface 21 of the rear half body 2 are designed so that the two half bodies 1 , 2 can cooperate with each other when moving between the first position and the second position.

[0012] The front half body 1 comprises a seat portion 10 terminating on a rear operating surface 11 of the front half body 1 , and the rear half body 2 comprises a seat portion 20 terminating on a front operating surface 21 of the rear half body 2 .

[0013] Each seat 10 , 20 is laterally delimited by two side walls 101 , 202 that are flat and parallel to each other.

[0014] refer to Figure 1B and Figure 2B Each of the articulated shoe lasts A1, B1 also includes an articulated assembly Ga, Gb, which keeps the two half bodies 1, 2 movably connected to each other and is arranged in the seat 10 of the front half body 1 and in the seat 20 of the rear half body 2.

[0015] The hinge components Ga and Gb include:

[0016] - a first element 3 connected to the front half 1;

[0017] - a second element 4 connected to the rear half 2;

[0018] A one-piece spring 5 made of phosphate steel, having a substantially C-shaped and curved central portion 50 , a first hook 51 attached to the first element 3 and a second hook 52 attached to the second element 4 .

[0019] The two articulated lasts A1 , B1 differ from one another, in particular with regard to the articulated assemblies Ga, Gb and the operating surfaces 11 , 21 of the two mating halves 1 , 2 .

[0020] The first articulated last A1 is also technically referred to as an “articulated last with a V-shaped hinge”.

[0021] refer to Figure 1 and Figure 1A In the first articulated last A1 , the shapes of the rear operating surface 11 of the front half body 1 and the front operating surface 21 of the rear half body 2 allow the two half bodies 1 , 2 to rotate relative to each other around the pivot axis X.

[0022] Specifically, the rear operating surface 11 of the front half body 1 and the front operating surface 21 of the rear half body 2 include:

[0023] - lower parts 111a, 121a adapted to engage with each other when the first articulated last A1 is in a first extended position;

[0024] - a central portion 112a, 122a, which is particularly shaped so as to produce a rotational coupling between the front half 1 and the rear half 2;

[0025] - upper portions 113a, 123a, which are separated from each other and which move away from the central portions 112a, 122a when the first articulated last A1 is in the first extended position.

[0026] The upper portions 113a, 123a define a space S that tapers toward the central portions 112a, 122a.

[0027] refer to Figure 1A When the two half-bodies 1, 2 are rotated relative to each other from the extended position to the retracted position, the upper parts 113a, 123a move closer, while the lower parts 111a, 121a move away.

[0028] The central portions 112a, 122a include a concave portion 112a extending along a circumferential arc and a convex portion 122a extending along a circumferential arc.

[0029] The circumferential arc of the convex portion 122a has a radius of curvature equal to that of the concave portion 112a, and extends at an angle greater than that of the circumferential arc of the concave portion 112a.

[0030] See also Figure 1B The first element 3 of the articulated assembly Ga of the first articulated last A1 comprises a pin 3a which is transversely mounted in the seat 10 of the front half 1 and to which the first hook 51 of the spring 5 is attached.

[0031] The second element 4 of the hinge assembly Ga of the first articulated last A1 comprises a pin 4a mounted transversely in the seat 20 of the rear half 2 , to which the second hook 52 of the spring 5 is attached.

[0032] For reasons that will become apparent in the following description, the reader's attention must be focused on the following two features of the first articulated shoe last A1 in the prior art:

[0033] a) the seats 10, 20 of the front half 1 and the rear half 2 terminate in the lower part 111a, 121a, the central part 112a, 122a and the upper part 113a, 123a of the operating surface 11, 21 of the half 1, 2 respectively;

[0034] b) The curved portion 50 of the spring 5 extends along a circular arc-shaped trajectory, and its camber Q is between 28 mm and 32 mm (see Figure 1C ).

[0035] In such a structural configuration, the curved portion 50 of the spring 5 of the hinge assembly Ga of the first hinged shoe last A1 partially protrudes into the space S defined by the upper portions 113a, 123a. Figure 1 .

[0036] Reference now Figure 2 and Figure 2A The second articulated last B1 is also technically referred to as an “articulated last with a sliding hinge”.

[0037] In the second articulated shoe last B1, the rear operating surface 11 of the front half body 1 and the front operating surface 21 of the rear half body 2 have cam surfaces 11b, 21b, and the shapes of the cam surfaces enable the two half bodies 1, 2 to slide and rotate relative to each other.

[0038] Still refer to Figure 2B , the first element 3 of the articulated assembly Gb of the second articulated last B1 comprises:

[0039] - a lever 30b having a first end 301b and a second end 302b, the first end 301b being formed with a slot 35b and the second end 302b being formed with a hole 36b;

[0040] - a first transverse pin 31 b mounted transversely in the seat 10 of the front half 1 and screwed into the slot 35 b of the lever 30 b;

[0041] - A second transverse pin 32b, which is mounted transversely in the seat 20 of the rear half 2 and is screwed into the hole 36b of the lever 30b.

[0042] The second element 4 of the articulated assembly Gb of the second articulated last B1 comprises a pin 4 b mounted transversely inside the seat 20 of the rear half 2 .

[0043] In this case, the first hook 51 of the spring 5 is attached to the first end 301 b of the lever 30 b of the first element 3 , whereas the second hook 52 is attached to the pin 4 b of the second element 4 .

[0044] The present invention is particularly concerned with the structure of the spring 5. As mentioned above, the spring 5 is currently made of phosphate steel. This monolithic structure leads to several disadvantages, which are particularly due to the method to be implemented to obtain a C-shaped spring 5 made of phosphate steel.

[0045] In fact, in order to manufacture this integral C-shaped spring 5, the following steps are required:

[0046] a) Provide steel strips;

[0047] b) performing a ball annealing step to soften the steel strip;

[0048] c) performing a bending step to bend the softened steel strip into a C-shaped spring;

[0049] d) performing a compression step in which the spring 5 is compressed laterally so that the spring 5 is laterally provided with flat sides suitable for rubbing against the flat walls 101 , 202 of the seats 10 , 20 without clearance;

[0050] e) performing a thermal tempering step, thereby reducing the hardness of the spring 5 and increasing its toughness;

[0051] f) A phosphating step is carried out to modify the outer surface of the spring so as to obtain phosphate crystals, which improve corrosion resistance and facilitate adhesion for subsequent painting operations.

[0052] The applicant has determined that the above-mentioned annealing, compression and heat tempering steps will cause internal cracks and defects in the molecular structure of the spring 5, thereby making the spring 5 brittle, thereby greatly compromising the efficiency and reliability of the overall steel spring 5.

[0053] Therefore, the spring 5 often breaks down or fails, and it is inevitable to replace the spring.

[0054] US2164054A describes a foldable last comprising a front part and a heel part hinged together, wherein the hinge flexibly holds the parts in an extended operative position or a folded inoperative position, as the case may be. Summary of the invention

[0055] It is through careful analysis of the problems affecting the integral spring 5 that the present invention has been devised, resulting in a new type of spring that is more efficient, more reliable and easier to manufacture.

[0056] In other words, the object of the present invention is to overcome the drawbacks of the prior art by designing an articulated last comprising an articulated assembly with a novel spring, which is efficient, reliable and safe.

[0057] In addition, another object of the present invention is to design an articulated shoe last having a hinge assembly with a spring, which is simple and quick to manufacture.

[0058] These objectives are achieved according to the present invention and the features listed in the attached technical solution 1.

[0059] Favorable results can be seen from the subordinate technical solutions.

[0060] The articulated shoe last according to the present invention is defined by Technical Solution 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] For the sake of clarity, the articulated shoe last according to the present invention is further described below in conjunction with the accompanying drawings, which are only for illustration and not for limitation purposes, wherein:

[0062] Figure 1 and Figure 1A Schematically showing a first articulated last according to the prior art in an extended position and a retracted position respectively;

[0063] Figure 2 and Figure 2A Schematically showing a second articulated last in an extended position and a retracted position, respectively, according to the prior art;

[0064] Figure 1B The hinge assembly of the first articulated shoe last according to the prior art is shown in detail;

[0065] Figure 1C The spring of the first articulated last according to the prior art is shown in detail;

[0066] Figure 2B The hinge assembly of the second articulated shoe last according to the prior art is shown in detail;

[0067] Figure 3 and Figure 3A Schematically showing a first articulated last according to the present invention in an extended position and a retracted position respectively;

[0068] Figure 4 and Figure 4A Schematically showing a second articulated last according to the present invention in an extended position and a retracted position respectively;

[0069] Figure 5 Schematically shows a spring of a first articulated last according to the present invention;

[0070] Figure 6 yes Figure 5 Cross-sectional view of the spring along the VV plane.

[0071] Hereinafter, elements identical with or corresponding to elements already described are denoted by the same reference numerals, and detailed descriptions are omitted. DETAILED DESCRIPTION

[0072] refer to Figure 3 , Figure 3A , Figure 4 and Figure 4A , shows a first articulated shoe last A2 and a second articulated shoe last B2, whose structural features are substantially the same as the first articulated shoe last A1 and the second articulated shoe last B1 of the prior art. Figure 3 , Figure 3A , Figure 4 and Figure 4A As shown, the elements of the articulated shoe last A2, B2 according to the present invention are the same as or correspond to the elements of the articulated shoe last A1, B1 already described in the prior art, such as the half bodies 1, 2, the seats 10, 20, the surfaces 11, 21, the articulated assemblies Ga, Gb, and are indicated by the same reference numerals. To reiterate, for the sake of brevity, a detailed description of these elements will be omitted.

[0073] The articulated lasts A2 and B2 differ from the articulated lasts A1 and B1 of the prior art in that they have a spring 6 which is different from the integral spring 5 of the prior art.

[0074] In fact, although still having a substantially C-shaped curved central portion 60, a first hook 61 connected to the first element 3 and a second hook 62 connected to the second element 4, the new spring 6 of the articulated last A2, B2 according to the invention is made of two pieces and comprises:

[0075] - inner metal wire 7;

[0076] - and an outer plastic coating 8 which completely covers the inner wire 7 .

[0077] See also Figure 6 The outer coating 8 made of plastic material comprises a flat side 80 which is in contact with the flat side walls 101 , 201 of the seats 10 , 20 of the half-bodies 1 , 2 .

[0078] The inner wire 7 is preferably made of steel and has a circular cross section with a diameter between 3 mm and 5 mm, preferably 4 mm.

[0079] The outer coating 8 made of plastic material is preferably made of polyethylene or acrylonitrile butadiene styrene or polystyrene.

[0080] The thickness of the outer coating 8 is 0.7 mm to 1 mm. It should be noted that the term "thickness" refers to the distance between the outer surface of the inner wire 7 and the outer surface of the outer coating 8.

[0081] In a preferred embodiment of the present invention, the inner wire 7 and the outer coating 8 are co-formed.

[0082] Therefore, the new spring 6 is realized by the following method:

[0083] - providing an inner metal wire 7;

[0084] - bending the inner wire 7 so that said wire extends along a substantially C-shaped trajectory identical to that of the spring 6 to be manufactured;

[0085] - placing the inner wire 7 in the cavity of a mould having the shape of the spring 6 to be manufactured;

[0086] - injecting molten plastic material into the mold cavity so that the plastic material adheres to and covers the inner metal wire 7;

[0087] - Waiting for the plastic material to solidify and harden, thereby defining the outer coating 8 of the spring 6 .

[0088] The novel spring 6 consisting of an inner wire 7 and an outer coating 8 has several advantages.

[0089] First, the inner wire 7, which is the core and elastic element of the spring 6, is simply bent, and does not need to be subjected to ball annealing, compression, and heat tempering like the strip used to manufacture the spring 5 in the prior art. Since the inner wire 7 does not undergo ball annealing, compression, and heat tempering, the internal structure of the inner wire 7 will not produce cracks or other defects that affect its strength.

[0090] Therefore, the applicant has found that the new spring 6 consisting of the inner wire 7 and the outer coating 8 is more reliable and efficient than the integral spring 5 of the prior art.

[0091] It is also worth pointing out that since the flat side 80 is machined on the outer coating 8 of plastic material, in order to obtain such a flat side 80, it is only necessary to appropriately design the cavity of the mold for injecting the plastic material without any compression step on the spring itself.

[0092] The spring 6 having the inner wire 7 and the outer coating 8 is suitable for use in the hinge assembly Ga of the first articulated last A2 and the hinge assembly Gb of the second articulated last B2.

[0093] Reference now Figure 3 , Figure 3A and Figure 5 The applicant has also designed some technical means suitable for solving the problems encountered when the spring 6 with the inner wire 7 and the outer coating 8 is arranged in the first articulated shoe last A2.

[0094] In order to understand this problem, it is necessary to point out that during the manufacturing process of the first articulated lasts A1, A2, after the first articulated lasts A1, A2 are assembled, an operation must be performed to remove the burrs in the upper parts 113a, 123a of the surfaces 11, 12, so that the upper parts 113a, 123a are completely smooth so that they can be in perfect contact when the first articulated lasts A1, A2 are in the retracted position. This burr removal operation is performed using a milling cutter or a hydrogen-oxygen flame.

[0095] If the first articulated last A2 and the spring 6 have the same structural configuration and the same dimensions as the first articulated last A1 and the associated integral spring 5 of the prior art, then the spring 6 with the inner wire 7 and the outer coating 8 will also have a curved central portion 60 that protrudes into the space S defined by the upper portions 113a, 123a of the surfaces 11, 12, and therefore, during the above-mentioned deburring operation, this space may be accidentally intercepted by tools or flames.

[0096] Obviously, since the spring 6 is provided with an outer coating 8 made of plastic material, such an accident will cause irreparable damage to the outer coating 8, thus requiring replacement of the spring 6 itself.

[0097] To address this issue, the applicant stipulates:

[0098] - the height of the spring 6 is lower than that of the integral spring 5 of the prior art; in other words, the curved central portion 60 of the spring 6 extends along a circular arc-shaped trajectory, and its camber T is between 16 mm and 21 mm;

[0099] The seats 10 , 20 of the half-bodies 1 , 2 end only on the lower portions 111 a , 121 a of the faces 11 , 21 of the half-bodies 1 , 2 and on the central portions 112 a , 122 a of the faces 11 , 21 of the half-bodies 1 , 2 .

[0100] In summary, the spring 6 is completely housed and safely placed inside the seats 10 , 20 of the two halves 1 , 2 and cannot be caught by the tools or flames used during the deburring operation.

[0101] Many changes and modifications of detail may be made to the present embodiments of the invention while remaining within the scope of the invention as expressed in the appended claims.

Claims

1. Articulated lasts for making shoes (A2, B2); The articulated shoe last (A2, B2) comprises: - a front half (1) and a rear half (2) which are movably mounted between a first extended position and a second retracted position; wherein the front half (1) has a rear operating surface (11) and the rear half (2) has a front operating surface (21); the operating surfaces (11, 12) of the two halves (1, 2) are suitably shaped so as to cooperate with each other during the movement of the two halves (1, 2) between the first position and the second position; the front half (1) comprises a seat (10) terminating at the rear operating surface (11) and the rear half (2) comprises a seat (20) terminating at the front operating surface (21); wherein each seat (10, 20) has two flat and mutually parallel side walls (101, 102); and - an articulation assembly (Ga, Gb) which keeps the two halves (1, 2) movably connected to one another and is arranged in the seat (10) of the front half (1) and in the seat (20) of the rear half (2); Wherein, the hinge assembly (Ga, Gb) comprises: - a first element (3) connected to the front half (1); - a second element (4) connected to the rear half (2); - a spring (6) which is substantially C-shaped, having a curved central portion (60), a first hook (61) connected to the first element (3) and a second hook (62) connected to the second element (4); It is characterized in that the spring (6) comprises: - an inner wire (7); and - an outer coating (8) of plastic material which completely covers the metal wire (7); wherein the outer coating (8) of plastic material comprises a flat side (80) which is in contact with the flat side wall (101, 201) of the seat (10, 20) of the half-body (1, 2).

2. The articulated shoe last (A2, B2) according to claim 1, wherein: The outer coating (8) is made of polyethylene or acrylonitrile-butadiene-styrene or polystyrene.

3. The articulated shoe last (A2, B2) according to claim 1 or 2, wherein: The inner metal wire (7) is made of steel.

4. An articulated last (A2, B2) according to any one of the preceding claims, wherein: The inner metal wire (7) has a circular cross-section with a diameter between 3 mm and 5 mm, preferably 4 mm; wherein the thickness of the outer coating (8) is between 0.7 mm and 1 mm.

5. An articulated last (A2, B2) according to any one of the preceding claims, wherein: The inner metal wire (7) and the outer coating are molded together.

6. An articulated last (A2, B2) according to any one of the preceding claims, wherein: The curved central portion (60) extends along a circumferential arc-shaped trajectory and has a crown (T) between 16 mm and 21 mm.

7. An articulated last (A2) according to any one of the preceding claims, wherein: The rear operating surface (11) of the front half body (1) and the front operating surface (21) of the rear half body (2) are shaped so as to allow the two half bodies (1, 2) to rotate relative to each other around the pivot axis (X); wherein the first element (3) of the hinge assembly (Ga) comprises a pin (3a) transversely mounted in the seat (10) of the front half (1), the first hook (61) of the spring (6) being attached to the pin (3a); Therein, the second element (4) of the hinge assembly (Ga) comprises a pin (4a) transversely mounted in the seat (20) of the rear half (2), and the second hook (62) of the spring (6) is attached to the pin (4a).

8. The articulated shoe last (A2) according to claim 7, wherein: The rear operating surface (11) of the front half body (1) and the front operating surface (21) of the rear half body (2) include: - lower parts (111a, 121a) adapted to engage with each other when the articulated last (A2) is in the first extended position; - a central part (112a, 122a) suitably shaped so as to produce a rotational coupling between the front half (1) and the rear half (2); - upper portions (113a, 123a) which diverge from each other from the central portion (112a, 122a) when the articulated last (A2) is in the first extended position, thereby defining a space (S) that tapers towards the central portion (112a, 122a).

9. The articulated last (A2) according to claim 8, when dependent on claim 6, wherein: The seat (10, 20) of the half-body (1, 2) ends only in the lower part (111a, 121a) of the face (11, 21) of the half-body (1, 2) and in the central part (112a, 122a) of the face (11, 21) of the half-body (1, 2).

10. The articulated last (B2) according to any one of claims 1 to 5, wherein: The rear operating surface (11) of the front half body (1) and the front operating surface (21) of the rear half body (2) have cam surfaces (11b, 21b) which are shaped so as to allow sliding and relative rotation between the two half bodies (1, 2); Wherein, the first element (3) of the hinge assembly (Gb) of the articulated shoe last (B2) comprises: - a lever (30b) having a first end (301b) and a second end (302b), the first end (301b) being formed with a groove (35b) and the second end (302b) being formed with a hole (36b); wherein the first hook (61) of the spring (6) is engaged with the first end (301b) of the lever (30b); - a first transverse pin (31b) mounted transversely in the seat (10) of the front half (1) and inserted in the groove (35b); and - a second transverse pin (32b) mounted transversely in the seat (20) of the rear half (2) and inserted into the hole (36b); Wherein, the second element (4) of the hinge assembly (Gb) of the second articulated shoe last (B2) includes a pin (4b), which is transversely mounted in the seat (20) of the rear half (2); wherein the second hook (62) of the spring (6) is connected to the pin (4b) of the second element (4).

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