Conveyors – chutes – skids – guides – and ways – Rollerways – Submerging and rising
Reexamination Certificate
1999-11-24
2002-04-02
Bidwell, James R. (Department: 3651)
Conveyors, chutes, skids, guides, and ways
Rollerways
Submerging and rising
C193S037000
Reexamination Certificate
active
06364086
ABSTRACT:
The invention relates to a chain of rolling elements comprising a plurality of rolling elements and an elongate carrier belt, wherein the carrier belt comprises a plurality of recesses for receiving the rolling elements, a plurality of retainers for retaining the rolling elements received in the recesses and at least one elongate flexible element for connecting the retainers and wherein two lateral edge portions and a central portion connecting them can also be distinguished on the carrier belt, the retainers being connected to the at least one flexible element in the lateral edge region of the carrier belt.
2. Background of the Invention
A chain of rolling elements of this type is known, for example, from Japanese patent laid-open print 5-52217 (1993) to Japanese patent application 3-235563 (1991). The known chain of rolling elements comprises a plurality of balls arranged in recesses in a carrier belt. Between each two successive balls there is arranged a retainer which comprises, on its sides leading or trailing in the longitudinal direction of the carrier belt, a respective retaining face for sliding engagement with the leading or trailing ball. The retainers are connected to one another by two flexible strip elements and form the carrier belt together with it.
The known ball chain has the advantage that the balls can be arranged in close succession, i.e. with minimal spacing from one another. The ratio of the ball diameter to the spacing between the centres of two adjacent balls is approximately 1:1. Owing to the resultant high ball density, the known ball chain has a high load-carrying or load-bearing capacity. However, the stiffening of the carrier belt accompanying the fastening of the two strip elements to the retainers in the region between two successive balls is disadvantageous. The strip elements of the carrier belt are able to react to bending of the carrier belt round an axis extending parallel to the transverse direction of the carrier belt, for example in the deflection portions of the race of a linear bearing, only in the region of their lateral contact with the balls but not in the region of their lateral fastening to the retainers.
The resultant relatively pronounced bending of the carrier belt in the region of its lateral contact with the balls leads to a corresponding restoring force of the carrier belt, resulting from the elasticity of the carrier belt material, into its rectilinear position. This restoring force influences the movement of the balls in the deflection portions of the race owing to the retaining of the balls by the carrier belt. In a linear bearing equipped with the known chain of rolling elements, the pronounced bending of the carrier belt can lead to more pronounced generation of noise and to increased friction between the strip elements and the guide grooves.
Further chains of balls with balls in close succession are disclosed, for example, in U.S. Pat. Nos. 2,897,021 and 3,292,981. In these ball chains also a retainer is arranged in each case between two successive balls, the retainer comprising a retaining face for sliding engagement with the leading ball as well as a retaining face for sliding engagement with the trailing ball.
A further non-generic chain of rolling elements is known from Japanese patent laid-open print 62-242126 (1987) to Japanese patent application 60-253865 (1985). In the chains of rolling elements known from
FIGS. 5 and 6
thereof, each rolling element is retained by two retainers associated with it and only with it. Therefore, between two successive rolling elements there are provided two physically separated retainers which are arranged in a central portion of the carrier belt with predetermined spacing from one another.
The carrier belt of the known chain of rolling elements has the advantage that it can be bent round an axis extending parallel to the transverse direction not only in the regions of its lateral contact with the rolling elements but also in the regions between two successive rolling elements. As the number of bending points is twice that in JP-A-5-52217 (1993), the carrier belt is bent less at each individual bending point with equal curvature of a deflection portion of the race and influences the running of the rolling elements to a correspondingly smaller extent and this results in smoother running of a linear bearing equipped with the known chain of rolling elements. The chain of rolling elements known from JP-A-62-242126 (1987) has the drawback, however, that the rolling elements are arranged in a loose succession, i.e. with relatively great mutual spacing, to provide the space required for the separate retainers. The ratio of the ball diameter to the spacing of the centres of two adjacent balls is approximately 1:1.5. The resultant lower density of rolling elements is accompanied by a corresponding reduction in the load-carrying capacity of the chain of rolling elements.
DE-PS 835 718 discloses a chain of rolling elements in which the spacing between successive rolling elements is about twice the diameter of the rolling elements. The rolling elements are retained by tongues arranged therebetween of a spring steel strip carrying them. A chain of rolling elements with rolling element spacing of similar size, i.e. similarly loose succession of rolling elements, is disclosed in U.S. Pat. No. 2,557,476.
DE 36 35 261 A1 describes a ball chain with average ball spacing. In other words, the ratio of the ball diameter to the spacing of the centres of successive balls is about 1:1.25. Each of the balls is associated with mutually separated retainers arranged between the balls. Therefore, the retainers are very small and can barely retain the balls.
The ball chain known from DE 29 06 128 A1 is formed from a plurality of chain units which are formed independently of one another and each serve to guide only one of the balls. This arrangement therefore results in a loose succession of balls. The orifices receiving the balls do not retain the balls. Therefore, the chain units also comprise guide blocks which are separate from the receiving orifices and centre the chain units in the ball channel and, in particular its deflection portions with respect to the running of the balls.
Reference is also made to DE 37 09 039 C2, DE 89 14 085 U and U.S. Pat. No. 2,566,421.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a chain of rolling elements which is distinguished by a high load-carrying or load-bearing capacity and also by smooth running.
According to a first aspect of the invention, this object is achieved by a chain of rolling elements comprising a plurality of rolling elements arranged in close succession and an elongate carrier belt with a plurality of recesses for receiving the rolling elements, a plurality of retainers for retaining the rolling elements received in the recesses, and at least one elongate flexible element for connecting the retainers, wherein the carrier belt can be split into two lateral edge portions and a central portion connecting them, wherein, moreover, the retainers are connected to the at least one flexible element in the lateral edge regions of the carrier belt, wherein, moreover, separate retainers are associated with successive rolling elements, and wherein at least one retainer associated with each rolling element is provided before and after each rolling element on the at least one flexible element in the longitudinal direction thereof. The term close succession of rolling elements is interpreted according to the foregoing discussion of the state of the art as a succession in which the ratio of the diameter of the rolling elements to the spacing of the centres of successive rolling elements is less than 1:1.5, preferably less than 1:1.25, most preferably approximately 1:1.
This solution principle is based on the combined effect of two groups of features. On the one hand, the carrier belt is flexibilized in the region between successive rolling elements since separate retainers are associated with each rolling element, and this has
Blaurock Günter
Pfeuffer Viktor
Schlereth Rudolf
Stender Hans-Georg
Bidwell James R.
Rexroth Star GmbH
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