Method for making an induction welding head and relative induction welding head

Abstract

Method for making an induction welding head (1 ), and relative welding head (1 ), the method comprising: providing an insulating support body (2) comprising a housing seat (3); applying an adhesive material (30) in the housing seat (3); providing a conductive element (5) having a groove (6) that develops along a main development line of the conductive element; filling the groove with filling material (40); inserting the conductive element (5) into the housing seat (3) with the groove (6) facing towards the housing seat (3); allowing the adhesive material (30) to harden to glue the conductive element (5) to the support body (2) and to fluid-tightly the groove (6); and melting the filling material (40) and allowing the filling material (40) to flow out of the groove (6) to create a conduit along the conductive element (5).

Description

[0001] DESCRIPTION

[0002] Title: METHOD FOR MAKING AN INDUCTION WELDING HEAD AND RELATIVE INDUCTION WELDING HEAD

[0003] Technical field of the invention

[0004] The present invention relates to a method for making an induction welding head for an automatic machine, for example, an automatic filling machine for containers for pourable products (for example, wine, milk, fruit juices, syrups, beverages, sauces, creams, yogurt, purees, preserves, vegetables, legumes, peeled tomatoes...).

[0005] State of the art

[0006] It is known a forming and filling machine of a container for pourable products by folding and heat-sealing a packaging sheet. The welding device that performs the transverse sealing comprises an induction welding head provided with a tubular conductive element (that is, internally hollow) which is bent into a "U" shape to form two distinct and separate sealing zones, between which a blade operates to execute the transverse cutting of the folded and sealed sheet. The tubular conductive element is embedded in a support body made of plastic material, which is overmolded around the same tubular conductive element with a circular cross-section. Part of the support body and part of the tubular conductive element are removed by milling to create the operative surface, which is substantially flat except for a pair of ribs protruding perpendicularly from the flat surface. It is also known a method for making an induction welding head, wherein, before overmolding the support body around the tubular conductive element, the tubular conductive element with a circular cross-section is mechanically processed by plastic deformation to form at least one flat wall in a central portion of the tubular conductive element.

[0007] Summary of the invention

[0008] The Applicant has observed that the known methods for making the induction welding head present one or more of the following disadvantages: waste of a large amount of "noble" material (in particular copper, which constitutes the conductive element), high production times and / or costs, especially related to the molding and / or plastic deformation phase of the tubular conductive element, low precision in the geometric dimensions of the conductive element and / or in the positioning of the conductive element relative to the support body (for example, due to misalignment of the conductive element in the mold). The Applicant has addressed the problem of making a welding head with high geometric precision and with a wide design freedom, particularly for the conductive element, in a fast and / or cost-effective manner.

[0009] According to the Applicant the aforementioned problem is solved by a method in accordance with the attached claims and / or according to the following aspects and embodiments.

[0010] According to one aspect the invention relates to a method for making an induction welding head.

[0011] Preferably the method comprises providing a support body made of electrically insulating material.

[0012] Preferably the support body comprises a housing seat.

[0013] Preferably the method comprises applying an adhesive material in said housing seat.

[0014] Preferably the method comprises providing a conductive element having a groove that develops along a main development line of the conductive element.

[0015] Preferably the method comprises filling said groove with filling material.

[0016] Preferably the method comprises inserting said conductive element into said housing seat with said groove facing towards said housing seat.

[0017] Preferably the method comprises allowing said adhesive material to harden to glue said conductive element to said support body and to fluid-tightly seal said groove.

[0018] Preferably the method comprises melting said filling material and causing said filling material to flow out of said groove to create a conduit along said conductive element. According to one aspect the invention relates to an induction welding head.

[0019] Preferably the induction welding head comprises a support body made of electrically insulating material.

[0020] Preferably the support body comprises a housing seat.

[0021] Preferably the induction welding head comprises a conductive element having a groove that develops along a main development line of the conductive element.

[0022] Preferably the conductive element is housed in said housing seat with said groove facing towards said housing seat.

[0023] Preferably the induction welding head comprises a layer of adhesive material interposed between said conductive element and said support body to glue said conductive element to said support body.

[0024] Preferably said layer of adhesive material fluid-tightly seals said groove to create a conduit along said conductive element.

[0025] According to the Applicant, the use of the filling material to fill the groove and its subsequent removal allows for the creation of the conduit along the conductive element in a simple, quick, and economical way, without the need to rely on a pre-existing tubular element (i.e. , one already equipped with a conduit), which would otherwise require plastic deformation or material removal operations.

[0026] In this way, the geometry of the conductor element is controllable with high precision, and it is also possible to give the conductor element a desired shape with a high degree of design freedom.

[0027] The gluing of the conductive element to the support body eliminates the need for the comolding technique and facilitates the creation of the conduit, which in the finished product is delimited by the conductive element and the adhesive material itself, that before the removal of the filling material, it is temporarily interposed between the filling material and the housing seat.

[0028] The invention, in one or more of its aspects, may feature one or more of the following preferred characteristics.

[0029] Preferably, said filling said groove comprises pouring said filling material in the molten state into said groove and allowing said filling material to cool to bring it into the solid state.

[0030] Preferably said filling material is solid at room temperature, for example it has a melting point greater than or equal to 30°C, more preferably greater than or equal to 35°C. Preferably said filling material has a melting point lower than 80°C, more preferably lower than or equal to 70°C, even more preferably lower than or equal to 60°C. This facilitates its melting.

[0031] Preferably said filling material has, at a temperature slightly above the melting point, a viscosity that facilitates the complete emptying of the groove.

[0032] Preferably said filling material is water-repellent and / or insoluble in water (for example, to facilitate the complete emptying of the groove using a high-pressure water jet).

[0033] Exemplarily said filling material is a wax, such as polyethylene wax or paraffin (melting point around 45°C), or a fat, such as trilaurin or glyceryl tridodecanoate (melting point around 46°C).

[0034] Preferably, the welding head comprises an electromagnetic flux concentrator, such as ferrite, e.g., soft / hard.

[0035] In one embodiment said flow concentrator is dispersed and / or incorporated into said support body.

[0036] In an alternative embodiment or in combination with the aforementioned embodiment, said flow concentrator is one or more sheets that partially cover said conductive element, more preferably interposed between said conductive element and said support body. Preferably said support body is made of thermally insulating material.

[0037] Preferably, said support body is made of a fiberglass-based material, for example vetronite (or glass epoxy), i.e. , a composite material comprising one or more layers (with crossed or non-crossed fibers) of fiberglass (or equivalent materials such as paper) embedded in a resin matrix (e.g., phenolic, epoxy, polyimide, or BT / epoxy). In this way it is ensured a desired rigidity and / or electrical and / or thermal insulation properties.

[0038] Preferably said housing seat is obtained by milling said support body.

[0039] Preferably said housing seat is located at a front face of said support body.

[0040] Preferably said conductive element is counter-shaped to said housing seat.

[0041] Preferably providing said conductive element comprises cutting and / or milling a bar of conductive material. In this way, high geometric precision can be achieved, even for complex geometries, in a simple and / or cost-effective manner.

[0042] Preferably, said conductive element is made of copper.

[0043] Preferably said housing seat comprises a bottom and an opening opposite to said bottom, located at a front face of said support body.

[0044] Preferably said adhesive material is a structural adhesive.

[0045] Preferably applying said adhesive material comprises applying said adhesive material in liquid or gel form, more preferably at least on said bottom of the housing seat.

[0046] Preferably, after said filling said groove, said filling material is flush with an outer surface of said conductive element. In this way, the conduit utilizes the entire cross-section of the conductive element.

[0047] Preferably, after said inserting said conductive element, said groove faces towards the bottom of the housing seat. In this way, the sealing of the conduit is facilitated.

[0048] Preferably, after said inserting of said conductive element, said adhesive material entirely fills every space of said housing seat interposed between said conductive element, including said filling material, and said housing seat. In this way, a strong bonding of the conductive element is achieved, while also providing an effective sealing of the conduit.

[0049] Preferably, after said inserting of said conductive element, said adhesive material extrudes from said housing seat at a front face of said support body. In this way, bonding and sealing of the conduit are promoted, also enabling a visual inspection of the complete filling of the housing seat.

[0050] Preferably, it is also provided that, after said allowing to harden, creating, for example through milling, an operational face, substantially flat, of said welding head by removing material from a front face of said support body and from an outer face of said conductive element (and possibly from said adhesive material protruding from said housing seat).

[0051] Preferably, at an outer face of said conductive element, the conductive element comprises one or more ribs protruding from said outer face and having development along said main development line of the conductive element. Preferably, said one or more ribs have a straight development along said main development line of the conductive element. Equally preferably, said one or more ribs have a curved development along said main development line of the conductive element.

[0052] Preferably the main development line of the conductive element is substantially U- shaped, more preferably lying on a plane.

[0053] Preferably, the support body comprises one or more channels in fluid communication with said conduit, more preferably a pair of channels in fluid communication with two respective ends of said conduit.

[0054] Preferably, melting said filling material comprises flowing a hot fluid, e.g., water at a temperature greater than or equal to 50°C, through said one or more channels, and progressively into said groove. In this way, the groove is emptied in a simple and / or rapid manner.

[0055] Preferably, said causing to flow occurs along at least one of said one or more channels. It is noted that said one or more channels serve both during the manufacturing phase of the conduction head, to introduce the hot fluid and / or use to flow the melted filling material, and during the normal operation of the welding head, to allow the cooling fluid to flow through the aforementioned conduit.

[0056] It is specified that some phases of the above-described method may be independent of the execution order indicated, except where a sequential or simultaneous execution of two or more phases is expressly required. Additionally, some phases may be optional. Furthermore, certain phases may be performed repetitively or may be executed in series or in parallel with other phases of the method.

[0057] Brief description of the figures

[0058] Figure 1 is a schematic and partial perspective view of an induction welding head according to the present invention.

[0059] Figure 2 is a schematic and partial sectional view of the welding head along the section plane ll-ll of Figure 1 .

[0060] Figure 3 is a schematic perspective view of some elements of the welding head shown in Figures 1 and 2. Figures 4-6 schematically show a partial section of the welding head in respective phases of the manufacturing method according to the present invention.

[0061] Detailed description of some embodiments of the invention

[0062] The features and advantages of the present invention will be further clarified by the following detailed description of some exemplary, non-limiting embodiments of the invention, with reference to the accompanying figures.

[0063] In the figures, it is exemplarily shown an induction welding head 1 according to the present invention. The welding head 1 is used, for example, in an automatic forming and filling machine for containers of pourable products, which is neither shown nor described, as it may be of a known type.

[0064] Preferably the welding head 1 comprises a support body 2 made of electrically and thermally insulating material.

[0065] Preferably the support body 2 comprises a housing seat 3 at a front face 4 of said support body 2.

[0066] Exemplarily the housing seat 3 has a main development line substantially U-shaped, lying on a plane, and comprising two substantially parallel branches connected by a curved section of the housing seat 3. Exemplarily a section of the housing seat 3 orthogonal to the main development line is substantially rectangular (fig. 4-6). Preferably the support body 2 comprises, at the front face 4, a cavity 11 positioned between the aforementioned two branches of the housing seat 3 to allow, in use, the insertion of a blade (not shown) that performs the transverse cutting of the folded and welded wrapping sheet, for example, in a known manner. Preferably the housing seat 3 comprises a bottom and an opening opposite the bottom, at the front face 4 of the support body 2.

[0067] Exemplarily the support body 2 is made of vetronite, also known as epoxy glass.

[0068] Alternatively, the support body 2 may be made of a homogeneous polymeric material, such as resin, for example, obtained through molding.

[0069] Preferably the welding head comprises an electromagnetic flux concentrator (not shown, as it is, for example, of a known type), such as ferrite, e.g., soft / hard.

[0070] In one embodiment, the flux concentrator is dispersed, for example homogeneously, within the support body and / or comprises one or more solid bodies embedded in the support body.

[0071] In one embodiment, the flux concentrator comprises one or more sheets that at least partially cover the conductive element and are positioned between the conductive element and the support body (e.g., interposed between the support body and the adhesive material described below).

[0072] Preferably the welding head 1 comprises a conductive element 5, exemplarily made of copper, having a groove 6 that develops, more preferably continuously, along a main development line of the conductive element 5.

[0073] Preferably the conductive element 5 is counter-shaped to match the housing seat 3. Preferably the main development line of the conductive element 5 is substantially U- shaped, more preferably lying on a plane, and comprises two welding branches that are substantially parallel to each other (except for a slight divergence at the two ends of the welding zone to counteract the well-known issue of weld shrinkage in these areas due to magnetic field deformation), connected by a curved section of the conductive element.

[0074] Preferably each welding branch of the conductive element 5 comprises, on an outer face 12 of the conductive element 5, a rib 13 protruding from the outer face 12 and extending linearly along the main development line of the conductive element 5.

[0075] Preferably the conductive element 5 is housed in the housing seat with the groove 6 facing the bottom of the housing seat 3. In an alternative embodiment, not shown, the groove may be oriented towards a lateral wall of the housing seat 3 or may be located at a corner of the conductive element 5 facing the bottom of the housing seat 3 (and thus be oriented both towards a lateral wall and the bottom of the housing seat 3).

[0076] Preferably the welding head 1 comprises a layer of adhesive material 20 (fig. 6) interposed between the conductive element 5 and the support body 2 to glue the conductive element 5 to the support body 2. Preferably, the adhesive material layer 20 seals the groove 6 to create a conduit along the conductive element 5.

[0077] Preferably the adhesive material is a structural adhesive.

[0078] Preferably the support body 2 comprises a pair of channels 31 in fluid communication with the respective two ends of the groove 6.

[0079] A method for manufacturing the induction welding head 1 according to the present invention will be described below.

[0080] Preferably it is provided providing the support body 2 with the housing seat 3. For example, the support body 2 can be made by cutting from a block of vetronite, obtaining the housing seat 3 by milling the support body 2 and the channels 31 by drilling orthogonally to the housing seat 3.

[0081] Preferably it is provided applying an adhesive material 30 in liquid or gel form to the bottom and / or side walls of the housing seat 3.

[0082] Preferably it is provided providing the conductive element 5 having the groove 6, for example by cutting and / or milling from a pre-existing copper bar, creating the groove 6 through milling. In an alternative embodiment, the conductive element 5 can be made through additive manufacturing or 3D printing.

[0083] Preferably it is provided temporarily filling the groove 6 with a filling material 40 in solid state, such as wax (paraffin) with a melting point of about 45°C. For example, the wax 40 is poured in molten form into the groove 6 and then left to cool at room temperature to bring it to the solid state. Preferably the filling material 40 is flush with an outer surface 41 of the conductive element 5 (fig. 4).

[0084] At this point, it is provided inserting the conductive element 5, including the solid filling material 40, into the housing seat 3 with the groove 6 facing towards the housing seat 3 (for example, facing the bottom of the housing seat 3). During insertion, the adhesive material 30, pushed by the conductive element 5, rises at least partially from the bottom along the side walls of the housing seat 3, until it exits the housing seat 3 at the front face 4 of the support body 2 (fig. 5). In this way, the adhesive material 30 completely fills every space of the housing seat 3 between the conductive element 5, including the filling material 40, and the housing seat 3. The filling material 40 prevents the adhesive material 30 from entering the groove 6.

[0085] At this point, it is preferably provided allowing the adhesive material 30 to harden to form the adhesive layer 20 that glues the conductive element 5 to the support body 2 and also seals the groove 6 tightly.

[0086] It is preferably then provided melting the filling material 40 and causing it to flow out of the groove 6 to create a conduit along the conductive element 5. In one embodiment, the filling material is melted and removed using a hot fluid, such as a liquid, for example water at a temperature of about 60°C, which is introduced into one of the channels 31 and progressively flows along the groove 6 until it exits the other channel 31 .

[0087] Alternatively or in combination, the filling material can be removed by placing the front face 4 of the welding head onto a heated element or by heating the entire welding head, e.g., using an oven, or by passing an electric current along the conductive element 5.

[0088] Preferably, it is finally provided creating, for example by milling, an operational face, which is substantially flat, by removing material from the front face 4 of the support body 2 and from the outer face 12 of the conductive element 5 (optionally also removing the adhesive material 30 that protrudes from the housing 3 at the front face 4 of the support body 2), simultaneously shaping the two ribs 13. The dashed line in figure 5 exemplarily shows the profile of the operational face and the material to be removed.

Claims

CLAIMS1. A method for making an induction welding head (1 ), the method comprising:- providing a support body (2) made of electrically insulating material, the support body comprising a housing seat (3);- applying an adhesive material (30) in said housing seat (3);- providing a conductive element (5) having a groove (6) that develops along a main development line of the conductive element;- filling said groove with filling material (40);- inserting said conductive element (5) into said housing seat (3) with said groove (6) facing towards said housing seat (3);- allowing said adhesive material (30) to harden to glue said conductive element (5) to said support body (2) and to fluid-tightly seal said groove (6); and- melting said filling material (40) and causing said filling material (40) to flow out of said groove (6) to create a conduit along said conductive element (5).

2. Method according to claim 1 , wherein providing said conductive element (5) comprises milling and / or cutting a bar of conductive material.

3. Method according to any of the preceding claims, wherein after said filling of said groove (6), said filling material (40) is flush with an outer surface (41 ) of said conductive element (5).

4. Method according to any of the preceding claims, wherein after said inserting of said conductive element (5), said adhesive material (30) entirely fills every space of said housing seat (3) interposed between said conductive element (5) and said housing seat (3).

5. Method according to any of the preceding claims, wherein after said inserting of said conductive element (5), said adhesive material (30) extrudes from said housing seat (3) at a front face (4) of said support body.

6. Method according to any of the preceding claims, wherein the support body comprises one or more channels (31 ) in fluid communication with said groove (6), wherein said melting of said filling material (40) comprises flowing a hot fluid through said one or more channels (31 ) and progressively into said groove (6) and wherein said causing to flow occurs along at least one of said one or more channels.

7. Method according to any of the preceding claims, further comprising, after said allowing to harden, creating an operational face, substantially flat, of said welding head byremoving material from a front face (4) of said support body (2) and from an outer face(12) of said conductive element (5).

8. An induction welding head (1 ) comprising:- a support body (2) made of electrically insulating material, the support body comprising a housing seat (3);- a conductive element (5) having a groove (6) that develops along a main development line of the conductive element, wherein the conductive element (5) is housed in said housing seat (3) with said groove (6) facing towards said housing seat (3);- a layer (20) of adhesive material (30) interposed between said conductive element (5) and said support body (2) to glue said conductive element to said support body, wherein said layer (20) of adhesive material (30) fluid-tightly seals said groove (6) to create a conduit along said conductive element.

9. Welding head (1 ) according to claim 8, wherein said conductive element (5) is made of copper, wherein said support body (2) is made of fiberglass-based material, and wherein said adhesive material (30) is a structural adhesive.

10. Welding head (1 ) according to claim 8 or 9, comprising a substantially flat operational face at a front face (4) of said support body (2) and an outer face (12) of said conductive element (5), said conductive element comprising a rib (13) protruding from said outer face (12) and having development along said main development line of the conductive element.

11. Welding head (1 ) according to any of the claims from 8 to 10, wherein said support body (2) comprises one or more channels (31 ) in fluid communication with said groove (6) to flow a fluid in said conduit.

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