1. Field of the Invention
The present invention relates to a method of making a spiral decorative element of metal, and a machine therefor.
In particular, such decorative elements, which are called pine-cones or baskets, are obtained from a plurality of bars, that are generally four or eight in number, circular or polygonal in their cross-section, in a desired length.
2. Description of Related Art
A method of making the so-called pine-cones is known e.g. by U.S. Pat. No. 5,676,013. According to that patent, straight bars are welded together at their opposite ends and axially cold twisted by turning them a first angle. Then, the bars are axially twisted by turning them in the opposite direction a second angle smaller than the first one, and axially compressing them at the same time or, preferably, after being turned. This method is performed by a machine, which comprises a couple of hydraulic cylinders having rods that are provided with clamping means to clamp the ends of the bars and are able to rotate in virtue of respective electric motors.
U.S. Pat. No. 6,009,738 discloses a manual or powered apparatus for cold forming a pine-cone. That apparatus uses opposite location means for the location of welded ends of straight bars, the one location means being fixed to a plate and the other location means being mounted at the end of a shaft which is connected to a crank or powered. The crankshaft can be coupled to an externally threaded coaxial shaft, so that both location means can travel, when the crankshaft rotates, to axially compress the bars that have been twisted when the crankshaft has been freely rotating. U.S. Pat. No. 6,009,738 claims the fixed location of a welded end of bars in the one direction and the movement of the same welded end in the opposite direction.
In both methods above mentioned the pine-cone swells when the bars are extended while they are twisted in one direction and in the other one, and they are curved by subsequent axial compression.
An automatic swelling formation, on one hand, damages quality and constant reproducibility of an end product, especially if the several bars come from a different raw material. On the other hand, such an automatic formation allows the pine-cones to be made always with the same either essentially spherical or almost cylindrical conformation.
The present invention aims to overcome these drawbacks by separating a bar bending step for the pine-cone swelling from the twisting step, in which the bars are given a spiral pattern.
Therefore, according to a first aspect of the invention there is provided a method of making a so called pine-cone spiral decorative element of metal, which is formed from a plurality of bars, generally four or eight in number, having circular or polygonal cross-section, cut in desired length, characterized by comprising steps of:
According to a second aspect of the invention there is provided machine for making a so called pine-cone spiral decorative element of metal, comprising, the one above the other:
The present invention will be described with reference to its preferred embodiment in connection with the accompanying drawings.
FIGS. 10 to 12 are a side view, an end view and a perspective view respectively, of an alternate of unfinished product to make a decorative element by the method according to the invention; and
FIGS. 13 to 15 are a side view, an end view and a perspective view respectively, of a product obtained by the method according to the invention embodied to the alternate of unfinished product in FIGS. 10 to 12.
With reference to the drawings, FIGS. 1 to 5 are views showing a first form of unfinished product and a first end product in the method according to the present invention. In
In
In a subsequent working step, welded ends 5, 5 of the bars 1 in the unfinished product 4 are twisted with a resulting mutual rotation of the one welded bar ends 5 to the other welded bar ends 5 by a desired angle. The end product obtained is indicated as 6 in
If, in the method according to the present invention, a mutual rotation is performed only in a direction with a result that the one ends 5 approach the other ends 5, a pine-cone with a cylinder-shaped central portion is obtained. If the mutual rotation is performed by a multiple of 90 degrees, a parallel relationship, except for the spring-back depending on the material, is obtained for the faces of the bars that have been twisted.
If, in the method according to the present invention, a mutual rotation is performed first in a direction and then in the other one, with a result that the one ends approach the other ends, a pine-cone with a sphere-shaped central portion is obtained. Preferably, the second rotation extends by an angle smaller than the first rotation and is offset to the same by a multiple of 90 degrees, always except for the spring-back depending on the material.
A machine according to the present invention for making the so called pine-cones spiral decorative elements of metal according to the invention is a composite machine shown in a perspective view in
The horizontal press 10 is essentially a hydraulic cylinder, whose rod 11 holds a die 12. A counter-die 13 is placed on the free surface 9. The counter-die 13 is retained against a support plate 14 which is fixed to the free surface 9 of the machine body 8 by suitable threaded couplings 15.
The die 12, the counter-die 13 and the support plate 14 are better seen in the perspective view of
This arrangement allows different size bars to be housed between die and counter-die. Further, by using a die and counter-die having a suitable height, a plurality of bars can be bent at the same time, thus reducing the machining time.
An elongated prismatic bench 19, sustained near its free end by a pedestal 20, is mounted in the front side of the machine body 8.
A screw device 21 and a vise 22, best shown in the enlarged perspective view of the
The screw device 21 is shown in
The vise 22, which is known and then not described in more detail, is designed to clamp the other welded bar ends 5. The end product 6 obtained according to the above method from the unfinished product in
Referring to FIGS. 10 to 12, that are a side view, an end view and a perspective view, respectively, there is shown a second form of unfinished product, i.e. an alternate of that one shown in
An unfinished product 34 is obtained by welding eight heart-shaped bars 33 at their free ends 32, 32. Then, welded ends 32, 32 of the bars 33 in the unfinished product 34 are twisted with a resulting mutual rotation of the one welded bar ends 32 to the other welded bar ends 32 by a desired angle. The second end product obtained by the method according to the present invention is indicated as 35 in
As above described, by making a so called preform in a horizontal press as that one shown in
The preceding description has to be intended as not limiting, and other modifications and alternates can be made without departing from the protection scope of the accompanying claims.
Number | Date | Country | Kind |
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RM 2004 A 000365 | Jul 2004 | IT | national |