| Title of Invention | "A PROCESS FOR OBTAINING A COIL SPRING" |
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| Abstract | An/ automotive suspension) coil spring (1) of any known shape—and defined by a' metal body wound into turns is provided on a lateral surface (2) with a coating (3) of polymeric material; the coating (3) being defined by a continuous 100 to 500 μm thick layer of paint (4) formed from a polymeric material of 50 to 100 Shore A hardness. The paint from which the coating (3) is formed may be a thermoplastic, e.g. powdered/ paint preferably selected from the group including: PVC, PU, PPA and mixtures thereof. In particular, the paint is selected from the following commercial products: Smaltoplast™, Abcite™, Plascoat PPA 571™, Desmopan™. The coating (3) is preferably applied to the surface (2) of the turns with the spring (1) at a relatively high temperature (about 200T250°C), e.g. by immersing the spring (1) in a fluidized-bed bath containing the paint, and with no preliminary application of adhesion promoter. |
| Full Text | The present invention relates to a process for obtaining a coil spring. The present invention relates to a coil spring, particularly for automotive suspensions, with a coating of polymeric material. As is known, automotive suspensions commonly feature coil springs, the end turn of which normally rests on a metal supporting plate integral with the shock-absorbers. Direct connection of the spring to a metal element, however, does not prevent the spring from knocking against the plate when the vehicle is moving, and the noise produced is far from negligible, particularly on vehicles of modern design in which great care is taken to eliminate any source of noise. To prevent the spring form knocking, special supports made of elastomeric material are used, and which are integral with the supporting plate and designed to receive the last turn of the spring. Such a solution, however, involves considerable cost and is therefore not used on recently designed vehicles. One possible solution - that of fitting the spring with a sheath of elastomeric or, at any rate, fairly pliable material - is difficult to actually implement, and practically impossible in the case of increasingly common variable-pitch springs. It is an object of the present invention to provide a coil spring, particularly for automotive suspensions, designed to eliminate the aforementioned drawbacks, and which in particular produces very little in-service noise, is cheap and easy to produce, and is effectively protected against corrosion. According to the present invention, there is provided a coil spring, particularly for an automotive suspension, comprising a metal body wound into turns, and a coating of polymeric material on a lateral surface of said turns; characterized in that said coating comprises a continuous layer of paint comprising a polymeric material at 50 to 100 Shore A hardness. Preferably, said layer of paint is of a thickness ranging between 100 and 500μm, and is formed from a material selected from the group comprising: PVC, PU, PPA, mixtures thereof and other mechanically equivalent polymers or copolymers. According to a preferred embodiment, said layer is formed from a thermoplastic polymeric material preferably selected from the group comprising the following commercial products : Smaltoplast™, Abcite™, Plascoat PPA 571™, Desmopan ™ and similar. The present invention relates to a process for obtaining a coil spring, particularly for an automotive suspension, comprising the steps of a) wounding a metal body into turns by hot permanent deformation; b) while the wound metal body is still at a relatively high temperature, painting on a lateral surface of said turns a polymeric coating made of a polymeric material of a selected hardness and thickness, wherein said polymeric material is chosen from the group consisting of PVC and PU having a Shore A hardness of 50 to 100; characterized in that said coating is obtained with a thickness ranging between 100 and 500 μrn, so that, at the same time, said coil spring is effectively protected against corrosion and the noise generated by the coil spring is greatly reduced; and in that, in combination, said painting step is carried out so that, owing to the adherence characteristics of the chosen polymeric material and of the difference in shrinkage of said polymeric material and of said metal body, the coating does not adhere completely to said lateral surface. WE CLAIM: 1} A process for obtaining a coil spring, particularly for an automotive suspension, comprising the steps of a) wounding a metal body into turns by hot permanent deformation; b) while the wound metal body is still at a relatively high temperature, painting on a lateral surface of said turns a polymeric coating made of a polymeric material of a selected hardness and thickness, wherein said polymeric material is chosen from the group consisting of PVC and PU having a Shore A hardness of 50 to 100; characterized in that said coating is obtained with a thickness ranging between 100 and 500 jura, so that, at the same time, said coil spring is effectively protected against corrosion and the noise generated by the coil spring is greatly reduced; and in that, in combination, said painting step is carried out so that, owing to the adherence characteristics of the chosen polymeric material and of the difference in shrinkage of said polymeric material and of said metal body, the coating does not adhere completely to said lateral surface. 2. A process as claimed in claim 1, wherein no preliminary application of adhesion promoters is carried out on said lateral surface of said turns before said painting step. 3. A coil spring, particularly for an automotive suspension, comprising a metal body wound into turns, and a coating of polymeric material on a lateral surface of said turns; wherein said coating is made of a polymeric material of PVC and/or PU with a Shore A hardness of 50 to 100 and a thickness of 100 to 500 μm; characterized in that, owing to the adherence characteristics of the chosen polymeric material and of the difference in shrinkage of said polymeric material and of said metal body, said coating does not adhere completely to said lateral surface; said coil spring being obtainable by the process of Claim 1. 4. A process for obtaining a coil spring substantially as herein described with reference to the accompanying drawings. 7. A coll spring substantially as herein described with reference to the accompanying drawings. |
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1274-del-1998-correspondence-others.pdf
1274-del-1998-correspondence-po.pdf
1274-del-1998-description (complete).pdf
1274-del-1998-petition-137.pdf
| Patent Number | 213739 | ||||||||
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| Indian Patent Application Number | 1274/DEL/1998 | ||||||||
| PG Journal Number | 03/2008 | ||||||||
| Publication Date | 18-Jan-2008 | ||||||||
| Grant Date | 11-Jan-2008 | ||||||||
| Date of Filing | 14-May-1998 | ||||||||
| Name of Patentee | REJNA S.P.A. | ||||||||
| Applicant Address | VIA BRERA 3, 20121 MILANO, ITALY | ||||||||
Inventors:
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| PCT International Classification Number | F16F 1/02 | ||||||||
| PCT International Application Number | N/A | ||||||||
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PCT Conventions:
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