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Low Cost Automation Tutorial

#086 Motion Mechanism Design - 3 : Conveyor Belt Brackets

Category : Drive mechanism design
September 9, 2011

A work transfer conveyor carries work pieces on the conveyor belt and hence needs support structures below the conveyor belt. This section explains the low cost work supports (belt support brackets) that are easily adjustable to conveyor height.

(1) Relative positions between belt support brackets and conveyor

In case of the work transfer conveyor shown as an example, work piece takes the following three types of actions on the conveyor belt at the three locations. At each location, a non-contact sensor monitors the presence or absence of work pieces to control the operation of the conveyor belt. Therefore, the conveyor belt needs support from underneath with the belt support to specifically stabilize the positions of the work pieces at the sensor locations (See Fig. 1):

  1. Placement
  2. Positioning
  3. Pre-ejection pause

[Fig. 1] Function of belt support brackets

(2) Belt support brackets shaped for easy adjustment

Functionally, the work transfer conveyor does not require precise parallel alignment between the top side of the conveyor belt and the base plate. Accordingly, the belt support bracket shapes are preferably designed under the assumption that the assembly will not be parallel. Additionally, there should be three separate belt support brackets to stabilize the three types of positions explained in (1) above, and each bracket should be designed to consist of two parts to allow height adjustment (see Fig. 2):

[Fig. 2] Typical easily height adjustable belt support bracket consisting of two parts

(3) Designing belt support brackets at low cost

The design cost should be minimized from the following points of view:

(1) Reduction in number of parts

Reduction in the number of parts is advantageous and minimizes manufacturing costs. For functional reasons, however, the number of belt support brackets is set at three. Hence, the three brackets should have identical shapes to minimize design and machining costs.

(2) Reduction of manufacturing cost

Parts manufacturing cost is divided into the material cost and machining cost to develop a low cost design.

- Part manufacturing cost minimization

Select a commercially available standard material that requires minimal outside machining. Two-millimeter thick cold-rolled steel sheets (JIS SPCC) are selected on the basis of the weight of the conveyed work pieces. SPCC sheets characteristically excel in dimensional accuracy, surface smoothness, and the workability properties of bending, drawing, cutting, and welding.

- Machining cost minimization

Machining cost minimization means reducing the time required for machining. This is almost synonymous with minimizing the amount of material removed. The bracket structure selected here is weld-reinforced for strength and requires no machining except for the drilling position adjustment holes (see Fig. 3):

[Fig. 3] Weld-reinforced belt support bracket