(1) Field of the Invention
The present invention pertains to a conveyor system comprising pairs of vertically spaced and horizontally oriented pulleys and belts that are positioned on opposite sides of a conveyor path. The belts wrap around the pulleys and engage with opposite sides of an object being conveyed by the conveyor, for example an empty plastic blow molded bottle, and convey the object along the conveyor path between the belts. More specifically, the present invention pertains to an apparatus that quickly adjusts the vertical positioning of the pairs of pulleys and belts on each side of the conveyor path to quickly adapt the conveyor for conveying different sized objects.
(2) Description of the Related Art
One type of horizontal belt conveyor that conveys objects in upright orientations between opposed, laterally spaced belts of the conveyor is disclosed in U.S. Pat. No. 5,896,977 which issued on Apr. 27, 1999, and is assigned to the assignee of the present invention and is incorporated herein by reference. This type of belt conveyor is basically comprised of pairs of vertically oriented upstream and downstream shafts where the upstream shafts are laterally spaced on opposite sides of the conveyor path and the downstream shafts are laterally spaced on opposite sides of the conveyor path. Each shaft has an upper and lower pulley mounted to the shaft. The pulleys are typically secured against rotation relative to the shafts by keyways formed in the shafts and keys inserted between the pulleys and shafts. In addition, the pulleys are secured against axial movement on the shafts by set screws on the pulleys or other equivalent mechanisms typically employed in securing a pulley to a shaft. Belts are wrapped around the upper pulleys and around the lower pulleys of the upstream and downstream shafts on each side of the conveyor path. One of the shafts on each side of the conveyor path, either the upstream shaft or the downstream shaft, is rotated by a motive source and rotates the other shaft through the driving engagement of the belts wrapped around the upper and lower pulleys of the two shafts. The shafts are all driven at the same speeds and the pairs of shafts on opposite sides of the conveyor path are driven in opposite directions so that the portions of the belts that mutually oppose each other on opposite sides of the conveyor path travel at the same speed in the downstream direction.
The lateral spacing between the pulleys and their belts and the vertical spacing between the pulleys and their belts is determined by the size of the object being conveyed by the conveyor. For example, in conveying empty plastic blow molded bottles, the shape of the bottle determines the positioning of the pulleys on their shafts. Plastic bottles of this type are used as containers for carbonated beverages and other types of beverages. The bottles usually have an upper throat opening that is threaded on its exterior for receiving a cap. As the bottle extends downwardly from the throat, it tapers outwardly along a neck to an annular shoulder defining the upper portion of the main receptacle or body of the bottle. However, the circumference or diameter of the main receptacle or body of the bottle does not always remain constant as the bottle extends downwardly from its shoulder to the bottom of the bottle. More frequently, producers of beverages contained in plastic bottles have designed their own bottle configurations to assist consumers in identifying their products and distinguishing the products of others. For example, the main body of a bottle may begin with a flat exterior circumferential surface just below the bottle shoulder and then may curve inwardly and outwardly as the body extends downward to the bottom of the bottle. The bottom of the bottle also typically has a flat exterior circumferential surface around the bottom that is generally dimensioned at the same size as the circumferential surface of the body just below the shoulder to give the bottle upright stability.
In conveyor systems of the type described above, the efficiency of the conveyor system is dependent on the speed in which it conveys objects through the conveyor system. In horizontal belt conveyors of the type described above, when the conveyor system is switched from conveying one bottle configuration to another bottle configuration it is often necessary to reposition the pulleys on their shafts so that the belts wrapped between the upper and lower pulleys of the upstream and downstream shafts will engage against portions of the bottle body that will hold the bottles securely between the belts in their upright orientations as they are conveyed down the conveyor path. In order to reposition the pulleys and their belts vertically on the shafts, the conveyor system must be shut down. The period of time that the conveyor system is shut down while vertical repositioning of the pulleys and belts is taking place significantly detracts from the time efficiency of the overall conveyor system. What is needed to overcome this disadvantage in horizontal belt conveyor systems is a method of quickly adjusting the vertical positions between the pulleys and their belts on the upstream and downstream shafts to decrease the down time of the conveyor system and improve its overall time efficiency.
The present invention overcomes the disadvantages of prior art horizontal belt conveyors by providing a horizontal belt conveyor in which the pulleys mounted on each of the vertically oriented shafts can be quickly adjusted vertically relative to each other
Each pair of vertically oriented upstream and downstream shafts and the pulleys and belts mounted thereon are supported on a base that can be laterally adjusted toward and away from the conveyor path. Each of the vertically oriented shafts has an upper pulley and a lower pulley mounted on the shaft. The pulleys are keyed to the shafts so that they will rotate with the shafts, however they are free to slide vertically along the lengths of the shafts.
The upper pulleys on the upstream and downstream shafts on each side of the conveyor path are sandwiched between a pair of plates that also move upwardly and downwardly over the shafts. In a like manner, the lower pulleys on the upstream and downstream shafts on each side of the conveyor plate are sandwiched between a pair of horizontal plates. Additional tensioning rollers are mounted between each pair of plates. The belts wrapped around the upper and lower pulleys on the upstream and downstream shafts on each side of the conveyor path are also positioned between the pairs of horizontal plates. By adjusting the vertical positions of the plates along the upstream and downstream shafts, the positions of the pulleys sandwiched between the plates are also vertically adjusted on the upstream and downstream shafts.
A vertical adjustment mechanism is mounted on the base of the conveyor and is operatively connected with each pair of horizontal plates that sandwich the upper and lower pulleys on each side of the conveyor path. The vertical adjustment mechanism includes a pair of vertically oriented racks that extend upwardly from the base and pass through each pair of plates. The vertical adjustment mechanism also includes a horizontal shaft mounted between each pair of horizontal plates and a pair of pinion gears mounted on the shaft. Each pinion gear meshes with one of the vertically oriented racks. One end of the shaft projects out from between the pair of horizontal plates and a hex head is secured to the end of the shaft. A ratchet wrench is provided that is specifically designed to mate with each of the hex heads on the shafts. Turning the hex head with the ratchet wrench causes the shaft and its attached pair of gears to turn. Turning the gears in this manner causes them to walk either vertically upwardly or downwardly along the vertically oriented racks depending on the direction of rotation of the shaft. This in turn causes the pairs of horizontal plates with the pulleys sandwiched between them to move vertically upwardly and downwardly along the vertically oriented shafts, thereby adjusting the vertical positions of the upper and lower pulleys and their belts relative to each other on each side of the conveyor path.
The conveyor is also provided with a vertically oriented scale adjacent upper and lower pulleys on each side of the conveyor path that provides a visual indication of the vertical positioning of the upper and lower pulleys. The vertical scale is mounted to the base of the conveyor by a pivoting connection that enables the scale to be pivoted away from the upper and lower pulleys to replace belts on the pulleys.
The horizontal belt and pulley conveyor discussed above enables the vertical positioning of the pulleys and their belts on upstream and downstream shafts to be easily and quickly adjusted, thus reducing the down time of the conveyor and improving its time efficiency.