The invention relates to a mechanical belt fastener according to the preamble of the main claim.
Belt fasteners of this type, made of strip steel for example, are known. They are usually sold pre-bent into a V-shape. The ends of the legs are pointed and directed inward at a certain angle. These fasteners are needed for joining conveyor belts together.
To create an articulated joint, the fasteners are inserted at both ends of a belt cut off at right angles, with the eyes fitting into one another combwise. The ends are then connected releasably or hinged and with articulation with one another by a hinge pin pushed through.
In contrast to the likewise known wire or belt hooks, which have legs and tips of different lengths and hence staggered (long-short-long), the use of such connectors has the disadvantage that the connecting strength is approximately 30-40% less or lower. This is due to the fact that the tips penetrate the belt to the same depth on both the top and the bottom of the belt, and perforate the belt along a line. In addition, the connector tips, which are coarser by comparison with wire hooks, cut through a relatively large number of the carcass fibers that contribute to the strength of the belt, especially when they penetrate hard belt materials.
Despite the disadvantages listed above, connectors or fasteners made of strip steel are frequently used since they result in a smoother and more covered joint. Further advantages include the abrasion resistance of the connectors as a result of the wider contact surface, for example in belts that move or run with sliding, i.e. in a slider bed.
The goal of the invention is to design a fastener according to the preamble of the main claim in such fashion that the joint strength and/or the loadability of the joint and its elasticity, especially with regard to channel pulleys over which the belts run, is considerably improved. This goal is achieved according to the invention in a fastner according to the species by virtue of its characterizing features as contained in the preamble of the main claim.
The subclaims show preferred embodiments of the invention.
The legs of the first and second rows of legs each have two different lengths, preferably up to a total of four different lengths, with these different length dimensions alternating with one another. During the assembly of the belt, the tips located at the ends of the legs penetrate the belt in two planes on the top and bottom of the belt, pass through the belt, and are then bent again on the other side. By virtue of this special arrangement, the belt is penetrated in up to four planes instead of only one. As a result of the penetration points being staggered, no uniform fracture line or perforation results in the belt tension support of the belt. The static connecting strength increases by up to 75% depending on the belt design.
An arrangement is preferred in which both the first and the second row of legs have different lengths that alternate with one another. Since the individual legs then have a total of four alternating lengths, the tips located on the extensions of the legs can penetrate four different planes. The different lengths are chosen in such fashion that the penetration points of the tips are located in different planes in both the transverse and lengthwise directions. As a result, the connecting strength is increased further.
The continuous strip in this embodiment is preferably located on the top of the belt, resulting in an advantageous effect when it passes around the pulleys. The interrupted strips are mounted on the bottom of the belt, resulting in a favorable effect during running, especially over convex pulleys. Additional attachment of the legs to a strip, even though it is interrupted, ensures that the tips can penetrate in a straight line even into the hardest belt materials without being bent or deflected. This also ensures that damage to the belt tensioning element is limited to an absolute minimum.
The two strips (continuous on the top of the belt and interrupted on the bottom of the belt) result in an increase in the clamping effect and likewise contribute to an increase in the joint strength, since the retention point of the joint is displaced away from the tips of the fasteners.
In conventional fasteners it is advantageous that when the joint is made in soft belts, a folding of up to ten degrees takes place at the ends of the fastners. The tips, mounted staggered, produce a support in the connecting area and thus prevent folding.
Another advantage of providing the interrupted strip is that the material thickness of the fastener can be reduced without adversely affecting the separating effect.
The preferred embodiments of the invention will now be described in greater detail with reference to the drawings.
FIG. 1 the fastener in the non-folded state;
FIG. 2 shows a fastener pre-bent in a V-shaped in a sectioned side view.
FIG. 3 is a sectioned side view of a mounted fastener; and
FIG. 4 is a perspective view of the two open ends of a belt, into each of which ends a four-member joining element has been inserted.
FIG. 1 is a schematic top view of the two ends of a strip in the non-folded and/or unbent state. Bending area 5, when bent, produces eyes or loops 8, each of which meshes combwise with the eyes or loops of a second fastener, said eyes or loops being connected together by a hinge pin 6.
The individual lengths of the legs of the rows are measured from bending area 5. The longest leg 12 of the fastener is located on the side, which is characterized by continuous strip 3. The third-longest leg 14 is likewise on this side. Legs 12, 14 are arranged alternately.
The second longest leg 22 and the shortest leg 24 are located on the side with interrupted strip 4. Legs 22, 24 are likewise arranged alternately.
In the embodiment shown in FIG. 1, the sequence of different leg lengths is as follows: 12-22-14-24, etc. A reversal or a different arrangement of this leg arrangement is possible and conceivable, for example 12-24-14-22, etc.
FIG. 2 shows a fastener in the prebent V-shape. It shows that points or tip ends 30 located on legs of different lengths are arranged in four different planes.
FIG. 3 shows a fastener in the mounted state in cross section. One open end of a belt is marked with reference numeral 1.
In FIG. 4 the arrangement of legs of different lengths is shown at ends 1, 2 of the belt. The perspective view shows the two open ends 1 and 2 of a belt into each of which a four-member element has been inserted for example. The parts that are identical to those in FIGS. 1 to 3 have the same reference numerals in FIG. 4. Reference numeral 6 refers to the coupling rod which links the two reinforced ends 1 and 2 of the belt after they have been fitted together combwise to form an endless belt.