Conveyor roller

Abstract

Conveyor roller (8), comprising: a roller tube (81), and an axle shaft (82), wherein the roller tube (81) is held rotatably over the axle shaft (82), an one-piece antistatic element (88) adapted to dissipate electrostatic loads from the roller tube (81) to the axle shaft (82).

Description

[0001] Conveyor roller

[0002] Background of the invention

[0003] The invention refers to a conveyor roller and a method of manufacturing a conveyor roller.

[0004] Conveyor rollers, in particular idler rollers without having an internal drive motor, are provided with a roller tube and an axle shaft, wherein the roller tube is held rotatably over the axle shaft.

[0005] A conveyor roller having an antistatic arrangement is described in DE 36 08626 A1 .

[0006] It is an object to provide a conveyor roller having an improved antistatic element.

[0007] Summary of the invention

[0008] The invention refers to a conveyor roller and a method according to the main claims; embodiments are subject to the subclaims and the description.

[0009] The invention proposes to use an one-piece antistatic element located between the roller tube and the axle shaft. By using an one-piece element, the costs for production and assembly can be reduced.

[0010] In an embodiment the antistatic element is made from a foamed material. The foamed material is cheap and has low weight and is at the same time providing sufficient volume to fill the area between the roller tube and the axle shaft.

[0011] In an embodiment the antistatic element having an extruded body, which is a cheap and easy way of producing an element fitting into the roller tube.

[0012] Brief description of the drawings

[0013] An example embodiment of the invention is described in more detail with the help of the figures; herein show fig. 1 a conventional conveyor zone in perspective view; fig. 2 a longitudinal section of an idler roller of the conveyor zone of figure 1 in two embodiments; fig. 3. an antistatic element of the roller according to figure 2; fig. 4 a blank of an antistatic element according to figure 3; fig. 5 cross-sections of antistatic elements in different embodiments. Detailed description of the invention

[0014] Figure 1 shows an exemplary conveyor zone 2, comprising several conveyor rollers 8 which are driven together. The rollers are attached to a common frame 6. For this purpose, one of the conveyor rollers 8 is designed as a motorized conveyor roller 8M. The motorized conveyor roller 8M is driven by a, in particular three-phase, motor arranged within the conveyor roller 8M. The remaining rollers 8 are idler rollers, not comprising an internal drive motor. Via one or more drive connectors, e.g. a drive belt, the conveyor rollers 8 of a conveyor zone 2 are drive- connected to each other and are jointly driven by the motorized conveyor roller 8M. An object 9 is linearly conveyed from an inlet I to an outlet O along a conveying direction d.

[0015] By means of a presence sensor 5, the presence of a conveyed object 9 arranged on the conveyor zone 2 can be determined. The presence sensor 5 does not necessarily cover the entire conveyor zone 2; it is sufficient if the presence of a conveyed object 9 within a partial area of the conveyor zone 2 is detected by the presence sensor 5. The presence sensor 5 thereby generates a sensor signal, which is connected via a signal line (not shown) to a zone controller (not shown).

[0016] Figure 2 shows a section of an exemplary idler roller 8 in longitudinal view in two embodiments. The roller 8 has a roller tube 81 , which is held rotatably around axle shaft 82 by means of a bearing 83. Attached to the roller tube 81 is a bearing housing 84. An endcap 85 fixed to the axle shaft 82 covers the bearing 83. The roller tube 81 and the axle shaft 82 are in particular made of a conductive material in particular metal.

[0017] The axle shaft 82 is hereby shown as one unitary shaft extending along the overall length of the roller 8. In an alternative embodiment the shaft may be split into two separate shaft ends, each on one of the ends of the roller 8.

[0018] Within the roller tube 81 an antistatic element 88 is provided. The antistatic element 88 provides at least temporarily a conductive connection between the roller tube 81 and the axle shaft 82 to dissipate electrostatic charge from the roller tube 81 .

[0019] In the embodiment of figure 2a the antistatic element 88 is held with play on the axle shaft 82 and in the roller tube 81 , so that low friction arises between the axle shaft 82 and the antistatic element 88 and between the antistatic element 88 and the roller tube 81.

[0020] Figure 3 shows an exemplary embodiment of the antistatic element 88 in more detail. The antistatic element 88 has a cylindrical shape with an cylindrical outer surface 88S. In one embodiment an outer diameter D88 of said cylindrical surface 88S matches to an inner diameter d81 of the roller tube 81 (figure 2a). A central bore 88B of the antistatic element 88 serves for accommodation of the axle shaft 82. An inner diameter d88 of said bore 88B matches with an outer diameter D82 of said axle shaft 82 (figure 2a).

[0021] In another embodiment an outer diameter D88 of said cylindrical surface 88S matches to a distance Y between an outer surface of the axle shaft 82 and the inner surface of the roller tube 81 (figure 2b). A central bore 88B as in the previous embodiment is not required. The antistatic element 88 is held between the shaft axle and the roller tube with a press fit. In particular the antistatic element rotates in a manner of a planetary gear.

[0022] The antistatic element 88 is made in one-piece from a foamed material. Here any kind of metal is suitable. But also material of lower conductivity is suitable. As an example the material is made from a polymer material, e.g. Polyethylene foam, which may be treated with additives so to achieve a required conductivity. It is to be noted, that merely a small conductivity is sufficient to dissipate the electrostatic loads from the roller tube 81 . As an example a total electrical resistance of the antistatic element 88 of max 30kOhm is sufficient.

[0023] The foamed material has the advantage of a large surface, which can contact the roller tube 81 and the axle shaft 82. At the same time the antistatic element 88 has low weight, which has advantages in production cost and energy efficiency (since the antistatic element 88 may be set into rotation with the roller tube 81).

[0024] The antistatic element 88 having an extruded body, as shown in figure 4.

[0025] For producing the extruded body, an extruded blank 88R is provided which is cut by a saw 7 into slices. The blanks 88R are commercially available in the market at a low price.

[0026] Manufacturing of the antistatic elements 88 is very easy and cost efficient.

[0027] In case of the embodiment of figure 2a, the shape of the antistatic element 88 is not limited to a cylindrical shape. There are other shapes possible, exemplary cross-sections of which are shown in figure 5. The above description of the inner diameter and the outer diameter may also be valid for the other embodiments. Here the antistatic element has at e.g. three (fig. 5a) or two (fig. 5b) sections of a cylindrical outer surface 88S.

[0028] The invention is applicable to rollers 8 in a roller conveyor, where the roller may be an idler roller 8 or a motorized roller 8M.

[0029] The invention is also applicable to rollers 8 in a belt conveyor where the roller 8 serves for driving or idling a conveyor belt. List of reference signs

[0030] 2 conveyor zone 5 presence sensor 6 frame 7 saw 8 conveyor (idler) roller 8M motorized roller 81 roller tube 82 axle shaft 83 bearing 84 bearing housing 85 end cap 88 antistatic element 88B central bore 88S cylindrical outer surface 88R blank 9 object D88 outer diameter of antistatic element d88 inner diameter of bore in antistatic element d81 inner diameter of roller tube

[0031] D82 outer diameter of axle shaft Y distance between axle shaft and roller tube d conveying direction I inlet O outlet

Claims

Claims1. Conveyor roller (8), comprising: a roller tube (81), and an axle shaft (82), wherein the roller tube (81) is held rotatably over the axle shaft (82), characterized by an one-piece antistatic element (88) adapted to dissipate electrostatic loads from the roller tube (81) to the axle shaft (82).

2. Conveyor roller (8) according to the preceding claim, characterized in that said antistatic element (88) is made from a foamed material.

3. Conveyor roller (8) according to any of the preceding claims, characterized in that said antistatic element (88) having an extruded body comprising a constant cross-section over its length.

4. Conveyor roller (8) according to any of the preceding claims, characterized in that said antistatic element (88) has at least a section of a cylindrical outer surface (88S),- wherein an outer diameter (D88) of the cylindrical surface (88S) matches with an inner diameter (d81 ) of said roller tube (81), or- wherein an outer diameter (D88) of the cylindrical surface (88S) matches with a distance (Y) between an outer surface of the axle shaft (82) and the inner surface of the roller tube (81).

5. Conveyor roller (8) according to any of the preceding claims, characterized in that said antistatic element (88) has a central opening (88B) having an inner diameter (d88) which matches with an outer diameter (D82) of said axle shaft (82).

6. Conveyor roller (8) according to any of the preceding claims, characterized in that said antistatic element (88) is held rotatably over said axle shaft (82) and / or over said roller tube (81), thereby at least temporarily contacting both of the axle shaft (82) and said roller tube (81) at once, or in that said antistatic element (88) is held rotatably between said axle shaft (82) and said roller tube (81), thereby at least temporarily contacting both of the axle shaft (82) and said roller tube (81) at once.

7. Method of manufacturing a conveyor roller (8), in particular a conveyor roller (8) according to any of the preceding claims, the method comprising the following steps:- providing a roller tube (81),- providing an axle shaft (82),- providing a blank (88R) comprising a constant cross-section over its length;- cutting the blank (88R) into slices to obtain an antistatic element (88);- inserting the antistatic element (88) into the roller tube (81), so that the roller tube (81) is contacting the antistatic element (88) from the inner side of the roller tube (81) and inserting the axle shaft (82) into a central opening (88B) of the antistatic element (88), so that the axle shaft (82) is contacting the antistatic element (88) with an outer side of the axle shaft (82).

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