GEAR WITH EXTRUDED METAL SHAFT FOR SUPPORTING SKEWERS AND MANUFACTURING METHOD

Description

/ 8 GEAR WITH EXTRUDED METAL SHAFT FOR SUPPORTING SKEWERS AND MANUFACTURING METHOD Field of invention

[001] The present invention belongs to the technical field of rotary transmission mechanical devices, more specifically to support and rotation systems for skewers used in automated barbecues, comprising over-injection molded gears associated with metal inserts obtained by extrusion. The invention also falls within the sector of manufacturing metal-polymer components applicable in rotary drive systems and automated cooking devices. Fundamentals of the invention

[002] Support and rotation systems for skewers are widely used in automated barbecues, generally employing mechanical assemblies composed of metal gears with round or rectangular holes, metal shafts coupled to plastic gears, which are responsible for transmitting torque from electric motors. Such assemblies usually involve bearings, bushings, and fastening elements, forming rotating systems that operate under high temperatures and aggressive environmental conditions, such as grease, heat, and food residues.

[003] In known techniques, the metal inserts used in these assemblies are frequently obtained by integral machining processes, which entails a more expensive process with limitations on feasible geometries. In the particular case of skewers with a triangular cross-section housing, for example, direct machining of shafts with internal triangular housings is extremely complex, expensive, and not very reproducible. Alternative processes such as wire EDM or internal and external broaching are unproductive and very expensive. Alternatively, if the shaft were integrally injected, the extraction angles required by the mold would cause undesirable clearances between the skewer and the housing, impairing the stability of the skewer during its rotation. Petition 870250055184, dated 06 / 30 / 2025, page 12 / 25 / 8

[004] Some known solutions use overmolded inserts, but generally with cylindrical, rectangular or hexagonal shapes, which do not offer an efficient mechanical fit, suitable for keeping the skewer rotating without excessive play. Furthermore, the application of extruded metal profiles, whose housing has a triangular cross-section and whose outer body has longitudinal grooves, specifically designed for functional anchoring in polymer overmolding processes, is not observed in current techniques.

[005] There is also a shortage of optimized manufacturing methods that combine metal profile extrusion where the most complex geometries are obtained with high precision, functional machining and overmolding, resulting in a gear integrated into the shaft with high mechanical and thermal performance, with productivity and high dimensional reproducibility.

[006] Given the limitations encountered in the previous technique, the present inventor, seeking to resolve the inconveniences observed in the manufacture of gears integrated into metal shafts for skewer rotation systems, developed a gear with an extruded metal shaft with a housing featuring a triangular cross-section and its outer body composed of longitudinal grooves, which undergoes functional machining, being subsequently incorporated into a plastic gear by overmolding. This solution meets the requirements of mechanical fastening, thermal resistance, geometric precision and ease of manufacture, especially in applications with skewers of triangular cross-section.

[007] In a search of the state of the art, we identified several documents that describe gear solutions for supporting skewers, among which we can highlight the following documents:

[008] Document MU9002054 describes an arrangement introduced in a bearing for a rotating barbecue skewer, consisting of a single cylindrical piece with internal cavities for housing the skewer tip, designed to reduce friction during rotation and allow the use of metal and disposable skewers. The bearing has a V-shaped recess to facilitate the fitting of the skewer, in addition to integrating with the system of Petition 870250055184, dated 06 / 30 / 2025, p. 13 / 25 / 8 rotating gears of the barbecue grill. The proposal focuses on reducing friction and increasing the versatility of the types of skewers used.

[009] Although applicable to the same technical field as the present invention, the cited document deals exclusively with the bearing and support of the skewer, not describing any type of extruded metal shaft, triangular housing or overmolding of a gear in a grooved metal insert. The utility model is limited to the support structure, being functionally and constructively distinct from the solution now claimed, which combines an extruded profile with machining and overmolding to form an integrated gear with a robust mechanical coupling function for triangular skewers.

[0010] Document BR 202023015044 describes a barbecue grill equipped with gears featuring two distinct types of fittings: a V-shaped slot for metal skewers and a wedge-shaped hole for wooden skewers. The proposal aims to offer versatility of use with different types of skewers, keeping them centered and stable during rotation, in addition to improvements in the construction of the rotating assembly, such as the use of mini motors, elastic rings, machined tubes, and washers to reduce friction.

[0011] Although it offers an efficient rotary system compatible with various types of skewers, the aforementioned document does not describe an extruded metal shaft with an internal triangular section and external longitudinal grooves, nor does it address the use of polymer overmolding on a metal insert or any manufacturing method involving extrusion, machining, and integrated molding. The technical proposal is limited to a direct fitting of the skewer into the gear, and is therefore structurally and procedurally distinct from the invention presented here, which seeks to solve coupling and production problems with greater robustness and geometric precision.

[0012] Thus, it is observed that prior art documents present solutions for the rotation and support of skewers, but none of them efficiently solves the technical problem related to the coupling of skewers with a triangular cross-section in rotating barbecue systems, in a simultaneously precise, resistant and economically viable way. The present invention proposes, as an innovative solution, a metal shaft obtained by extrusion, equipped with a housing with a cross-section Petition 870250055184, dated 06 / 30 / 2025, page 14 / 25 / 8 substantially triangular transverse shaft for skewer coupling, and an outer surface with longitudinal grooves specifically designed to promote mechanical anchoring in the overmolding process. This shaft is subsequently incorporated into a gear molded from polymeric material, forming a robust assembly with improved fixation, high torque resistance, and excellent geometric precision, especially adapted to withstand rotational stresses in aggressive thermal environments, maintaining a minimum clearance for skewer fitting, so that the reduced clearance minimizes unwanted noise or movement. Additionally, the manufacturing process based on extrusion, cutting, machining, and molding allows for high productivity, excellent dimensional reproducibility, and an optimized process when compared to exclusively machined or injection-molded methods. Utility model summary

[0013] The present invention relates to a gear for supporting rotating skewers, composed of a metal shaft obtained by extrusion, equipped with a housing with a substantially triangular cross-section, intended for coupling skewers with compatible geometry. The outer surface of the shaft is longitudinally grooved, so as to allow its mechanical incorporation into a gear molded by over-injection of polymeric material, forming a functional assembly. The assembly can be complemented by support and fastening elements, such as a bearing, bushings, threaded stop bushing, washer and screw.

[0014] The invention further comprises a manufacturing method that includes the steps of extruding the metal profile with suitable geometry, cutting into segments, machining the ends to form functional fittings, and overmolding the gear onto the metal shaft. The shaft can be subjected to heat or surface treatments to increase its hardness and wear resistance. The invention also contemplates the possibility of using different polymeric materials for the gear so that they are resistant to temperature, wear, and low noise during operation. Petition 870250055184, dated 06 / 30 / 2025, page 15 / 25 / 8 Brief description of the drawings

[0015] The characteristics and advantages of the extruded metal shaft gear for supporting skewers and manufacturing method intended for automated barbecues, according to the present invention, will become more readily apparent from the detailed description below, provided by means of a non-limiting example, with reference to the attached schematic drawings, which illustrate one embodiment of the invention, without, however, limiting its scope.

[0016] Figure 1 shows the isometric view of the extruded metal profile (1a), with triangular section (1.1) and longitudinal grooves (1.2), used as raw material for the manufacture of the shaft (1).

[0017] Figure 2 shows the isometric view of the machined metal shaft (1) from the extruded profile (1a), with details of the housing (1.1) and the grooves (1.2).

[0018] Figure 3 shows the isometric view of the shaft and overmolded gear assembly (2a) formed by the overmolded gear (2) incorporating the metal shaft (1).

[0019] Figure 4 shows the exploded isometric view of the complete skewer support system (10), with all components identified.

[0020] Figure 5 shows the assembled unit with a cross-section, highlighting the integration of the shaft (1), gear (2), bearing (3), bearings (4), stop bushing (5) and screw (7).

[0021] Figure 6 shows the rear isometric view of the skewer support system (10) mounted on the fixing plate (9);

[0022] Figure 7 shows the isometric view of the shaft and gear assembly (2a) mounted on the fixing plate (9) and with the skewer (8);

[0023] List of references: Complete skewer support system; Extruded metal shaft (insert); Petition 870250055184, dated 06 / 30 / 2025, page 16 / 25 / 8 1.1 Housing with triangular cross-section; 1.2 Longitudinal grooves in the shaft; 1a Extruded profile; Gear molded by over-injection; 2a Overmolded shaft and gear assembly; Bearing; Bearing; Stop bushing; 5.1 Thread of the stop bushing; Washer; Screw; Skewer; Mounting plate or gear support. Description of the invention

[0024] The present invention consists of a gear for supporting rotating skewers (10), comprising an extruded metal shaft (1) used as an insert, associated with an over-injection molded gear (2) of polymeric material. The invention is particularly applicable in automated barbecues that use rotating systems for uniform cooking of food, being designed to be compatible with skewers (8) of substantially triangular shape, guaranteeing mechanical and thermal resistance, dimensional precision with consequent reduction of noise and unwanted movements of the skewer (8), as well as associating benefits regarding productivity and repeatability in the manufacture of gear transmission systems (10) for supporting rotating skewers.

[0025] The metal shaft (1), represented in figures 1 and 2, is obtained from an extruded metal profile (1a), with a cross-section configured to incorporate two distinct functional regions: an internal housing (1.1) with a substantially triangular geometry, intended for fitting the skewer (8); and an external surface with longitudinal grooves (1.2), arranged along its external length, with the function of promoting mechanical fixation between the insert and the polymeric material during the overmolding process. Petition 870250055184, dated 06 / 30 / 2025, page 17 / 25 / 8

[0026] After the metal profile (1a) is extruded, it is cut into segments with a predetermined length and then undergoes a machining process at the ends, in order to create functional fittings and interfaces with the other elements of the system, such as bearings (3), bushings (5) and rollers (4), as illustrated in figures 4 and 5.

[0027] In the next step, the shaft (1) is positioned in a mold for plastic overmolding, where it receives the molding of a gear (2) in polymeric material, forming the assembly (2a), as shown in figure 3. Overmolding is performed with polymeric materials selected from polyamide (PA), polyacetal (POM), polypropylene (PP), polycarbonate (PC) or polyethylene terephthalate (PET), with or without fiber reinforcement or mineral fillers, in order to guarantee thermal resistance, dimensional stability and low noise during operation.

[0028] The assembly (2a) can be mounted on the complete system (10), which also includes additional elements such as: bearing (3), through which the shaft rotates and the assembly is fixed to the plate (9); bearings (4) between the shaft and the bearing that reduce friction and minimize unwanted noise; stop bushing (5) with thread (5.1) that acts as a position limiter; washer (6) and screw (7) that hold the assembly together, as shown in figure 5.

[0029] Optionally, the metal shaft (1), after extrusion and before the overmolding stage, may be subjected to heat or surface treatments in order to increase its hardness and wear resistance, especially considering its operation in environments with high temperatures and constant friction. Among the possible treatments, the following stand out: T6 type heat treatment, conventional anodizing, hard anodizing or plasma electrolytic oxidation (PEO), all compatible with metal alloys such as aluminum.

[0030] The geometry of the triangular housing (1.1) inside the shaft (1) allows for precise coupling of the skewer (8), promoting efficient torque transmission with minimal backlash, which avoids vibrations and noise during rotation. The choice of a substantially triangular geometry also facilitates the positioning of the skewer, Petition 870250055184, dated 06 / 30 / 2025, page 18 / 25 / 8 preventing it from slipping and promoting greater stability in the cooking of food.

[0031] The longitudinal grooves (1.2), present on the outer surface of the shaft (1), perform a relevant mechanical function by acting as physical locking elements during the overmolding process, increasing the mechanical adhesion between the polymeric material and the metal insert. This anchoring reduces the risk of slippage or independent rotation of the gear (2) in relation to the shaft (1), guaranteeing the functional integrity of the assembly (2a) during prolonged use.

[0032] The industrial application of the present invention comprises automated or semi-automated barbecue grill systems used in commercial, industrial or domestic establishments, where repeatability in the grilling process, uniform rotation control and ease of assembly and disassembly of the skewers are sought. The assembly (10), composed of the shaft (1), gear (2), bearing (3) and other fastening components, can be implemented in rotating modules coupled to grills, conveyors or multiple sets of skewers aligned in series.

[0033] It should also be understood that the extruded metal shaft gear assembly for supporting skewers (10), according to the present invention, is susceptible to modifications and variations in form, materials and manufacturing processes, all of which remain within the scope of protection defined by the appended claims, which form an integral part of this descriptive report.

[0034] Furthermore, the construction details provided here as examples may be replaced by technically equivalent elements, provided that they do not detract from the functional and structural essence of the invention now claimed. Petition 870250055184, dated 06 / 30 / 2025, p. 19 / 25

Claims

1 / 2 CLAIMS 1. GEAR FOR SUPPORTING SPIKES, characterized by comprising a metal shaft (1) obtained by extrusion, having a housing (1.1) with a substantially triangular cross-section, said shaft (1) being used as an insert incorporated into a gear (2) molded by over-injection of polymeric material.

2. GEAR according to claim 1, characterized by the metal shaft (1) obtained by extrusion having longitudinal grooves (1.2).

3. GEAR according to any one of claims 1 to 2, characterized in that the overmolding is carried out with a polymeric material selected from the group consisting of: polyamide, polyacetal, polypropylene, polycarbonate or polyethylene terephthalate, modified with mineral filler or fiberglass.

4. GEAR according to any one of claims 1 to 6, characterized in that the assembly (10) includes a bearing (3) positioned on the shaft (1).

5. GEAR according to any one of claims 1 to 6, characterized in that the assembly (10) includes at least one bearing (4) disposed between the bearing housing (3) and the shaft (1).

6. GEAR according to any of claims 1 to 6, characterized in that the assembly (10) includes a stop bushing (5) having a thread (5.1), said bushing (5) being positioned between the shaft (1), the bearing (4), a washer (6) and a screw (7).

7. METHOD FOR MANUFACTURING A GEAR FOR SUPPORTING SPIKES, characterized by comprising the steps of: Petition 870250055184, dated 06 / 30 / 2025, page 20 / 25 2 / 2 (i) extrusion of a metal profile (1a), preferably in aluminum, with a substantially triangular internal cross-section and longitudinal grooves on its external surface; (ii) cutting the extruded profile into segments with defined length to form the metal shafts; (iii) machining of the ends of the shaft (1) to form functional fittings; and (iv) positioning the shaft (1) in a mold followed by overmolding of polymeric material to form a gear (2) incorporated into said shaft (1).

8. METHOD according to claim 7, characterized in that the metallic shaft (1) is subjected, after extrusion and before overmolding, to a treatment selected from the group consisting of: T6 type heat treatment, hard anodizing, conventional anodizing, or plasma electrolytic oxidation (PEO). Petition 870250055184, dated 06 / 30 / 2025, page 21 / 25

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