WO2017192329A1

WO2017192329A1 - Conveyor for reducing take-up load in the returnway

Info

Publication number: WO2017192329A1
Application number: PCT/US2017/029565
Authority: WO
Inventors: Gilbert J. Maclachlan; Abraham L. MILLER
Original assignee: Laitram, L.L.C.
Priority date: 2016-05-05
Filing date: 2017-04-26
Publication date: 2017-11-09
Also published as: CN109071117B; CN109071117A; EP3452393A1; EP3452393A4

Abstract

Components of a conveyor system designed to reduce take-up tension in a returnway of a conveyor. A snub roller in the returnway engages and drives a portion of the conveyor belt at a speed that is faster than the speed of a drive for the conveyor belt. A weighted roller between a drive and a synchronized sprocket tied to the drive alternatively reduces take-up load in a conveyor belt.

Description

CONVEYOR FOR REDUCING TAKE-UP LOAD IN THE RETURNWAY

Related Applications

The present application claims priority to US Provisional Patent Application No. 62/332,086, filed May 5, 2016 and entitled "Conveyor for Reducing Take-Up Load in the Returnway", the contents of which are herein incorporated by reference.

Field of the Invention

The present invention relates generally to power-driven conveyor belts, and more particularly to devices for reducing take-up load for radius conveyors that go around a curve.

Background of the Invention

Radius conveyors are designed to go around a curve. Radius conveyors require take-up tensioning to prevent belt disengagement at the drive sprockets. Take-up tensioning refers to maintaining the belt tension necessary to efficiently transfer power from a drive to the conveyor belt. Belt tension that is too low causes the drive to slip and reduces the energy transferred from the drive to the conveyor belt. Belt tension that is too great causes excessive force on the belt, increasing the likelihood that the conveyor belt will break. Snub rollers and S-shaped roller configurations are used to tension the conveyor belt in certain areas.

Generally, take-up tension tends to exponentially increase the load on a curved belt throughout the turn section on the radius conveyor, shortening the lifespan of the belt and potentially causing failures.

Summary of the Invention

The present invention provides a system for reducing-take up load in a returnway of a conveyor. In one embodiment, a snub roller in the returnway engages and drives a portion of the conveyor belt at a speed that is faster than the speed of a drive for the conveyor belt. In another embodiment, a weighted roller between a drive and a synchronized sprocket operating at the same speed as the drive reduces take-up load in a conveyor belt.

According to one aspect, a conveyor system comprises a conveyor belt trained around belt-guiding members to form a circuit having a carryway and a returnway, a drive for the conveyor belt and a powered snub roller spaced from the drive in the returnway for driving the conveyor belt, wherein the snub roller has a speed that is faster than the speed of the drive.

According to another aspect, a conveyor system comprises a conveyor belt trained around belt-guiding members to form a circuit having a carryway and a returnway, a drive for the conveyor belt, a synchronized sprocket spaced from the drive in the returnway for driving the conveyor belt, the synchronized sprocket operating at the same speed as the drive and a weighted roller between the drive and the synchronized sprocket.

According to another aspect, a method of reducing take-up load in a returnway of a conveyor comprises the steps of moving conveyor belt through a circuit using a drive and engaging the conveyor belt in using a snub roller near an outfeed of the drive, wherein the snub roller moves faster than the drive.

According to another aspect, a method of reducing take-up load in a returnway of a conveyor comprises the steps of driving a conveyor belt using a drive sprocket operating at a first speed, driving a synchronized sprocket that engages the conveyor belt at the first speed and wrapping the conveyor belt around a movable weighted take-up roller between the drive sprocket and the synchronized sprocket.

Brief Description of the Figures

These features of the invention, as well as its advantages, are better understood by referring the following description, appended claims, and accompanying drawings, in which:

FIG. 1 is a schematic view of an outfeed portion of a conveyor including a snub roller for reducing take-up in the returnway;

FIG. 2 is a schematic view of an outfeed portion of a conveyor including a

synchronized sprocket for reducing take-up in the returnway.

Detailed Description of the Invention

The present invention provides a system for reducing take-up load in a returnway of a conveyor. The present invention will be described below relative to an illustrative embodiment. Those skilled in the art will appreciate that the present invention may be implemented in a number of different applications and embodiments and is not specifically limited in its application to the particular embodiments depicted herein.

FIG. 1 shows an outfeed portion 10 of a conveyor system according to an

embodiment of the invention. The conveyor system includes a conveyor belt 20 trained around and driven by one or more drive sprockets 30 or other suitable drive. The conveyor belt 20 is in the form of a circuit with an upper conveying portion, forming a carryway for conveying product, and a lower returnway portion below and generally parallel to the conveying portion. A snub roller 40 is placed along the returnway portion near the drive sprockets 30 to ensure that the conveyor belt 20 properly engages the drive sprocket 30.

According to one embodiment, the snub roller 40 is powered to optimize take-up tension. In the embodiment of FIG. 1, the snub roller positively engages the conveyor belt 20 or frictionally engages the conveyor belt 20. The snub roller 40 applies a load to the conveyor belt, so that Tl is greater than T2. The illustrative snub roller 40 drives the conveyor belt 20 at a speed that is faster than the speed of the drive 30. In one embodiment, the snub roller 40 is between about 5% and about 15% faster than the drive, and preferably about 10% faster than the drive 30. In this manner, the tension in the conveyor belt in the region Tl between the drive 30 and the snub roller 40 is greater to ensure adequate engagement between the conveyor belt and the drive 30, but tension in the conveyor belt after the snub roller in region T2 is lower to prevent high loads in the turn sections and minimize load through the returnway. In addition, the faster snub roller prevents the reduction of back tension during belt speed acceleration or belt elongations, preventing disengagement of the conveyor belt at these times. Tension before the drive in region T3 is higher than the tension in both areas Tl and T2.

For a snub roller 40 that frictionally engages the conveyor belt, the roller surface can be adjusted to have a higher friction. For example, the snub roller can have a high-friction material on its outer surface to create a desired amount of back tension.

FIG. 2 shows another approach to reducing take-up load in a returnway of a conveyor, while allowing high take-up load in the drive sprocket. The conveyor includes a modular plastic conveyor belt 120 that goes over a nosebar 122 or other reversing element to a drive sprocket 130 below the nosebar 122 for driving the conveyor belt. The drive sprocket 130 is mounted on a drive shaft 131. A motor turns the drive shaft 131 to spin the sprocket at a selected speed, driving the conveyor belt 120. The conveyor also includes a synchronized sprocket 150 mounted on a synchronized shaft 151. The synchronized sprocket 150 operates at the same speed as the drive sprocket. In one embodiment, the synchronized sprocket can be a slave sprocket mounted on a slave shaft connected to the drive shaft 131 of the drive sprocket 130 and driven therefrom. Because the synchronized sprocket 150 operates at the same speed as the drive sprocket 130, the number of rows of belts remains the same between the two shafts 131, 151. The conveyor returnway further includes a plurality of belt guides, shown as rollers 160, 162, 164. A first roller 160 is located at the outfeed of the drive sprocket 130, above the drive sprocket. The second roller 162 is above the synchronized sprocket near the infeed to the synchronized sprocket. A third roller 164 guides the belt at the outfeed of the synchronized sprocket 150. A weighted, freely-rotating take-up roller 170 is mounted between the first two rollers 160, 162 in the returnway and wraps the conveyor belt in this area. The weighted take-up roller 170 is adjustably mounted to allow movement up and down to accommodate the conveyor belt. For example, the belt can change due to temperature, wear, water absorption or other factors, and the weighted take-up roller accommodates changes in the belt length in the area between the drive sprocket 130 and the synchronized sprocket 150. For example, the axles of the weighted take-up roller can be mounted in slots 180in the conveyor frame to allow movement of the weighted take-up roller. In one embodiment, the weighted take-up roller 170 has a range of between about one and about six inches of movement, though the invention is not so limited. The driven synchronized sprocket with a weighted roller between the drive and synchronized sprocket prevents high take-up load from the drive sprocket from being transferred to the remainder of the returnway.

The synchronized sprocket and the drive sprocket can be different sizes, as long at each moves the same number of belt modules per minute.

In another embodiment, the conveyor omits a nosebar and the drive sprocket is located at the end of the carryway. A synchronized sprocket can be mounted in the returnway a selected distance away from the drive sprocket and is driven at the same speed as the drive sprocket, as described above. A guide roller guides the belt at the exit of the drive sprocket and another guide roller guides the belt at the exit of the synchronized sprocket. A weighted take up roller is mounted in a slot or other accommodating device between the first guide roller and the synchronized sprocket. The illustrative configurations reduce the influence of returnway take-up load on the belt carryway load, allowing high take-up loads in the drive sprocket of a conveyor but preventing loads from going into the returnway of the conveyor belt. In this manner, the design prevents disengagement of the conveyor belt at the drive while increasing the lifespan of the conveyor belt.

The scope of the claims is not meant to be limited to the details of the described exemplary embodiments.

Claims

WHAT IS CLAIMED IS:

1. A conveyor system, comprising:

a conveyor belt trained around belt-guiding members to form a circuit having a carryway and a returnway;

a drive for the conveyor belt; and

a powered snub roller spaced from the drive in the returnway for driving the conveyor belt, wherein the snub roller has a speed that is faster than the speed of the drive.

2. The conveyor system of claim 1, wherein the snub roller has a speed that is between about 5% and about 15% faster than the speed of the drive.

3. The conveyor system of claim 1, wherein the snub roller frictionally drives the conveyor belt.

4. A conveyor system, comprising:

a drive for the conveyor belt;

a synchronized sprocket spaced from the drive in the returnway for driving the conveyor belt, the synchronized sprocket operating at the same speed as the drive; and a weighted roller between the drive and the synchronized sprocket.

5. The conveyor system of claim 4, wherein the weighted roller is mounted in a slot to allow the weight roller to move up and down.

6. The conveyor system of claim 5, wherein the slot between about one inch and about six inches.

7. The conveyor system of claim 5, further comprising a guide roller between the drive and the weighted roller.

8. The conveyor system of claim 5, further comprising a guide roller between the synchronized sprocket and the weighted roller.

9. The conveyor system of claim 4, wherein the synchronized sprocket is a slave sprocket tied to the drive.

10. A method of reducing take-up load in a returnway of a conveyor, comprising:

moving conveyor belt through a circuit using a drive; and

engaging the conveyor belt in using a snub roller near an outfeed of the drive, wherein the snub roller moves faster than the drive.

11. The conveyor system of claim 10, wherein the snub roller has a speed that is between about 5% and about 15% faster than the speed of the drive.

12. A method of reducing take-up load in a returnway of a conveyor, comprising:

driving a conveyor belt using a drive sprocket operating at a first speed;

driving a synchronized sprocket that engages the conveyor belt at the first speed; and

wrapping the conveyor belt around a movable weighted take-up roller between the drive sprocket and the synchronized sprocket.