PROCESS FOR THE MANUFACTURE OF A SEALING GASKET FOR A REFRIGERATOR

Abstract

The present invention relates to a process for the manufacture of a sealing gasket for a refrigerator, which simultaneously uses at least three extruders to form in a single operation a sealing gasket. The extruders simultaneously feed, in an extrusion die, a rigid or semi-rigid polymer, a flexible polymer and a mixture of a binder polymer and a magnetic material, for simultaneously forming the sealing gasket and, wherein a magnetizable zone is fully embedded within the gasket. After the sealing gasket has been formed in the extrusion die, it is cooled in a cooling section and then passed to a magnetization step to cause permanent magnetic fields and to ensure that the sealing gasket is fully magnetized.

Claims

1. A process for the manufacture of a sealing gasket for a refrigerator comprising: Providing an extrusion die for forming a sealing gasket; Providing a first extruder for feeding a rigid or semi-rigid polymer material for forming a rigid or semi-rigid zone in the sealing gasket; Providing a second extruder for feeding a flexible polymer material for forming a flexible zone in the sealing gasket; Providing a third extruder for feeding a mixture of a binder material and a magnetic material to provide a magnetizable zone to the sealing gasket; Coupling the first extruder, second extruder and third extruder with the extrusion die; Extruding simultaneously the rigid polymer material, the flexible polymer material and the mixture of the binder material and magnetic material into the extrusion die for simultaneously forming the sealing gasket in a continuous strip including the rigid zone and the flexible zone, said magnetizable zone remaining fully embedded or in predefined sections in the flexible zone; Cooling the sealing gasket in a cooling section after it has been formed in the extrusion die; Passing the gasket to a magnetization step to provoke permanent magnetic fields and ensure that the gasket is fully magnetized; and, Cutting the magnetized sealing gasket into sections of pre-established lengths.

2. The process as claimed in claim 1, wherein the rigid polymer material is polypropylene, rigid PVC, polyethylene, ABS (acrylonitrile butadiene styrene), HIPS (high impact polystyrene), PA (polyamide) or a mixture thereof.

3. The process as claimed in claim 1, wherein the flexible polymeric material is flexible PVC, EVA (ethylene-vinyl acetate or ethylene vinyl acetate), TPV (thermoplastic vulcanized), TPU (thermoplastic polyurethane), TPE (thermoplastic elastomers), polyethylene or mixtures thereof.

4. The process as claimed in claim 1, wherein the binder material is: EVA (ethylene-vinyl acetate or ethylene vinyl acetate), PVC, chlorinated polyethylene, TPU (thermoplastic polyurethane), TPV (thermoplastic vulcanizate) or TPE (thermoplastic elastomers).

5. The process as claimed in claim 1, wherein the magnetic material is strontium ferrite or barium ferrite.

6. The process as claimed in claim 1, wherein the cooling step is carried out in a cooling tub in a temperature range of between 10 to 15 Celsius.

7. The process as claimed in claim 1, including the step of: soldering portions of magnetized sealing gaskets to assemble a structure or frame to be installed in the cooling door or in those surfaces that requires be sealed with a sealing gasket.

8. The process as claimed in claim 1, wherein the magnetic material is in the form of micrometric particles with a diameter between 100 and 2500 nanometers.

9. The process as claimed in claim 1, wherein the magnetic material is in the form of nanometric particles with a diameter between 1 and 100 nanometers.

10. The process as claimed in claim 1, further comprising, providing a fourth extruder for extruding a rigid polymer material or a semi-rigid polymer material mixed with a pigment, to form a section rigid section or a semi-rigid section of color or a section with a flexible color polymer material.

11. The process as claimed in claim 10, wherein the semi-rigid material is plasticized PVC, polyethylene or polypropylene.

12. The process as claimed in claim 10, wherein the pigment is iron oxide or chromium oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] These and other objectives and advantages of the present invention will be more clearly understood from the following detailed description together with the accompanying flowcharts, wherein:

[0029] FIG. 1 is a schematic diagram of a first process embodiment for the manufacture a sealing gasket, in accordance with the present invention; and,

[0030] FIG. 2 is a schematic diagram of a second embodiment of the process for the manufacture of a sealing gasket, in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Making now reference particular to FIG. 1, there is shown in schematic flowchart a first embodiment of the manufacturing process of a sealing gasket which comprises: three extruders 10, 12, 14, which are coupled in coincidence with an extrusion die 16, having the desired shape of the sealing gasket.

[0032] As is known in the art, in an extrusion process, a polymer material from a hopper is fed in solid form into de barrel of the extruder. The material is gradually melted and is then forced into a die, which shapes the polymer with a pre-set geometric profile. According to the process of the present invention, a first extruder 10 melts and feeds a rigid or semi-rigid polymer material for forming a rigid or semi-rigid zone in the sealing gasket. That is, the sealing gasket may be formed of two flexible materials or of different hardness. This rigid or semi-rigid zone is usually attached to or attached to the cabinet of a refrigerator (not shown). Said rigid zone being formed of polypropylene, rigid PVC, polyethylene, ABS (acrylonitrile butadiene styrene), HIPS (high impact polystyrene), PA (polyamide) or a mixture thereof.

[0033] The second extruder 12 feeds and melts a flexible polymer material for forming a flexible zone in the sealing gasket. This flexible zone normally contacts the refrigerator door (not shown) when the door is closed, providing a seal between the door and cabinet. Said rigid zone being formed of flexible PVC, EVA (ethylene-vinyl acetate or ethylene vinyl acetate), TPV (thermoplastic vulcanized), TPU (thermoplastic polyurethane), TPE (thermoplastic elastomers), polyethylene or mixtures thereof.

[0034] Finally, the third extruder 14 feeds and melts a mixture of a binder material such as: EVA (ethylene-vinyl acetate or ethylene vinyl acetate), PVC, chlorinated polyethylene, TPU (thermoplastic polyurethane), TPV (thermoplastic vulcanizate) and a magnetic material such as: strontium ferrite or barium ferrite, forming an area of a magnetizable material. Strontium ferrite or barium ferrite can be in the form of micrometric particles whose diameter is between 100 and 2500 nanomethers or nanometric particles (nanoparticles) whose diameter is between 1 and 100 nanometers.

[0035] All of these materials are simultaneously extruded by means of the first extruder 10, second extruder 12, and third extruder 14 which are coupled with the extrusion die 16, for simultaneously forming the sealing gasket in a continuous strip including the rigid or semi-rigid zone and the flexible zone. During this operation the magnetizable section is completely embedded or in sections pre-established with the flexible zone.

[0036] The extrusion die 16 is designed to receive the flows of the three materials in a stable form, and direct it into the cavities necessary to give the desired shape to the product (sealing gasket). The flow of the three materials is pushed by the three extruders 10, 12, 14, at the beginning of the extrusion line.

[0037] Once the newly formed gasket has been formed in the extrusion die 16, the product has acquired its final shape and requires cooling. At this stage, the sealing gasket passes to a cooler 18 where it is cooled with water, in a temperature range of 10 to 15 degrees Celsius. At this stage the sealing gasket already has its final shape and when cooled it maintains its definitive dimensions. After the cooling step, air is additionally used to dry the product and prevent the water from being passed to the next process steps.

[0038] Once the package has cooled, it goes into a magnetization step. In this case, the sealing gasket is passed through a magnetizing machine 20 to cause permanent magnetic fields and to ensure that the sealing gasket is fully magnetized.

[0039] The gasket is pulled by a pulling machine (not shown), which is located after the magnetizing machine 20 pulling the product being formed in the extrusion die 16, applying a constant tension or pull to the product to maintain it moving. The speed of the pulling machine is controlled because a higher drag speed affects the dimensions and quality of the product.

[0040] Thereafter, the sealing gasket is cut in sections by means of a disc cutter 22 according to predetermined dimensions and with an angle of 45 at its ends and, for the preparation of the product to the next production step. The cutting machine 22 has a controller which is monitoring the progress of the sealing gasket and determines the time to perform the cutting process on an programmed length. At the start of the cutting process, the advance of the sealing gasket is stopped and two cutting blades (not shown) are advanced to make the cut and after the cut said cutting blades are retracted again, restarting the magnetic seal advance.

[0041] Once the cuts of the sealing gasket (not shown) are made according to the preset dimensions, the cut sections are welded in a welding machine 24 to assemble a structure or frame to be installed in the cooling door or in those surfaces that requires be sealed with a sealing gasket.

[0042] Finally, the finished product is stored or packed (warehouse 26) for delivery.

[0043] In a second embodiment of the present invention (FIG. 2), the sealing gasket manufacturing process may utilize four or more extruders. That is, there may be included a fourth extruder 28 which extrudes a rigid polymer material as described above or semi-rigid polymeric materials, for example a plasticized (semi-rigid and flexible) PVC, polyethylene, or polypropylene mixed with a pigment such as iron oxide, chromium oxide, either to form a rigid section or a semi-rigid section of color or a section with a flexible color polymer material.

[0044] From the foregoing, although two embodiments of a manufacturing process for refrigerator sealing gasket have been described, it will be apparent to those skilled in the art that other possible advances or modifications may be made, which may be considered within the given field by the following claims.