MXPA98010636A - Method and apparatus to reduce the generator noise the accumulation of vehicles in a transportable system - Google Patents

Abstract

An apparatus and method for reducing the noise generated by colliding conveyor vehicles, comprising urethane buffers and a method for fixing them to the portions of the vehicles that do not make contact with other vehicles when the vehicles are accumulated, is described. The shock absorbers extend from the vehicles at a distance sufficient to make contact with a similar shock absorber on an adjacent vehicle when one vehicle rolls against another. The shock absorbers do not prevent the portions that normally make contact with the vehicles from coming into contact, but only absorb a portion of the kinetic energy of the moving vehicle to reduce the risk generated when the contact portions of the trucks come together, and the presence of these shock absorbers does not adversely affect the separation of vehicles in the accumulator line.

Description

METHOD AND APPARATUS TO REDUCE THE NOISE GENERATED BY THE ACCUMULATION OF VEHICLES IN A CONVEYOR SYSTEM The present invention is directed to a method and apparatus for reducing the noise caused by vehicles colliding with each other in the accumulation portion of a conveyor line and more specifically to a method and apparatus for reducing the noise caused by the vehicle crashes without significantly altering the separation between vehicles in the accumulation line.

BACKGROUND OF THE INVENTION Power and free conveyor systems consisting of a power rail and a free rail and a pair of trucks capable of traveling along the free rail and supporting a vehicle are well known. Each header truck in a power and free system includes a driver ratchet portion that extends toward the power rail and that can be engaged by a ratchet driven by a chain of movement on the power rail. When the pusher pawl and the driving pawl are engaged, the trolley is pushed along the free rail by the moving power chain. When the driving pawl is retracted, or otherwise uncoupled from the pawl, the truck stops moving. Power and free conveyors often include sections or accumulation trucks where a number of vehicles can be stored in a contact relationship or closely spaced away from the main portion of the conveyor system until they are required. In order to accumulate the vehicles, it is necessary to uncouple the driving pawls of the trolleys supporting the vehicles from the pusher pawl. This is usually achieved by placing the accumulation section of the truck at a different elevation to that of the main portion of the rail so that the vehicle directed to the accumulation portion will roll downwardly away from the pusher until it runs towards a fixed object. The slope should be increased enough to ensure that the vehicle moves quickly away from the pusher to avoid traffic jams and provide a sufficiently high speed to the vehicle to ensure it continues to roll along the accumulation section of the rail until it makes contact with a catch or other vehicle. Additional vehicles can be accumulated in this way until the accumulation section of the rail is full. However, because vehicles are periodically removed from the downstream end of the accumulation section, new vehicles can be continuously accumulated. The trucks and vehicles are made of steel or similar alloys and consequently they are very heavy. Each pair of trolleys supports a vehicle that in turn is very heavy and may be supporting a heavy workpiece at any given time. Such vehicles have a large amount of symmetrical energy when they roll along the accumulation section of the conveyor, and this energy must be dissipated in order to stop the vehicle. While vehicles and trolleys are made of metal, a significant amount of energy derived from each crash between the vehicles dissipates as sound waves and each impact produces a relatively high noise. Because a conveyor line can have multiple accumulation portions and a plant can have multiple conveyor lines, each equipped with multiple accumulators, the noise produced by the accumulation of the vehicles is substantial and frequent. This noise can be annoying for anyone in a plant where accumulators are used, and, for employees who need to work very close to these accumulators, the noise can have adverse health effects as well. The high frequencies generated by this metal-to-metal contact can be particularly harmful to the ear.

In addition, trucks often do not accumulate at regular intervals. Therefore, the sound of each successive impact can be surprising for employees who are nearby. An employee who is startled by such surprise noises may have difficulty concentrating on his work. Attempts have therefore been made to reduce the noise created by these accumulations. The normal solution is to coat the metal surfaces that are usually in contact, with rubber or a similar material that absorbs the impact of the crashes. Although this can reduce the noise problem to a certain degree, the separation between adjacent vehicles in the accumulation line also increases, especially when sufficient cushioning material is used to reduce the noise level by a considerable amount. This increased separation changes the location of each truck in the accumulation line and makes it difficult for the system controller to keep track of the vehicles. In addition, this altered spacing can prevent the vehicles from properly aligning with other elements of the conveyor system, such as the unloading platforms along the accumulation rail. In addition, adding these materials to existing systems usually requires that the trucks be modified to accommodate the cushioning. This is often prohibitive from the point of view of costs. It is therefore desirable to reduce the noise generated by the accumulation of vehicles on a conveyor line without adversely affecting the separation of the vehicles, and whose noise reduction can be used in existing systems without modifying the vehicles too much.

BRIEF DESCRIPTION OF THE INVENTION The present invention addresses these and other problems and comprises an improved transport vehicle having a number of elastic shock absorbers fixed to portions of vehicles that do not contact other vehicles when vehicles are accumulated. The dampers are configured so as to make contact with each other before the metal contact surfaces of the vehicles collide. The shock absorbers can be made from u? size large enough to absorb a large portion of the force of impact between vehicles, and also their placement away from the surface that normally make contact, prevents them from significantly increasing the separation between vehicles in a line of accumulation . In addition, the shock absorbers are preferably made of a material of some elastic shape so that the sound generated by its impact is smaller and at a lower frequency than the sound generated by metal with metal.

It has been found that the noise generated by the accumulation of vehicles can be reduced to an acceptable level in this way and that it is not necessary to completely eliminate metal-to-metal contact. In a preferred embodiment, the buffers are made of urethane and can be reconditioned to existing vehicles by bolting the openings on the trucks used in general to connect the vehicle's support platform to the trucks. The shock absorbers include a fastening portion that fits between two separate walls on the existing trolleys. A hole is provided in the fixing portion that is aligned with the existing holes in the truck, and a bolt is passed through these aligned openings to hold the damper in place. The shock absorbers also include a main body portion, much of which is disposed above and below the body of the truck. The dampers are sized to make contact before any other portions of the trucks contact and absorb a portion of the impact energy. By attaching these shock absorbers to the portions of the trucks that do not usually make contact, a significant noise reduction can be achieved without adversely affecting the separation between the trucks.

Therefore, a primary object of the present invention is to provide a method and an apparatus for reducing the noise produced when two objects collide. Another object of the present invention is to provide a method and an apparatus for reducing the noise produced by the accumulation of vehicles on a conveyor line. A further object of the present invention is to provide a shock absorber for absorbing part of the force of a moving vehicle as it collides with another object. Another object of the present invention is to reduce the noise generated by colliding vehicles without significantly changing the spacing between the vehicles. • Another additional object of the present invention is to provide a method for reducing the amount of high frequency noise generated by the collision of two metallic objects. Another object of the present invention is to provide a method for mounting the dampers on the transport vehicles that reduce the noise generated by the accumulation of the vehicles without significantly increasing the separation between the vehicles in an accumulation line.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention will be apparent from the reading and understanding of the following detailed description of a preferred embodiment together with the accompanying drawings in which: Figure 1 is a pictorial view of a truck shock absorber in accordance with the present invention. Figure 2 is a side elevation view of a number of vehicles in an accumulation line equipped with the dampers shown in Figure 1. Figure 3 is a detail elevation view, partially in section, of two of the trucks shown in Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY With reference to the drawings, which purpose is to illustrate a preferred embodiment of the present invention only and not for the purpose of limiting the same, Figure 1 shows a. damper 10 having a main body portion 12 with a width Wl and a fixing portion 14 with a width W2 formed of a single piece of material, preferably urethane. The main body portion 12 includes an outwardly curved front contact wall 16, the parallel side walls 18, the parallel upper and lower walls 20 and a normal rear wall 22 relative to the side walls 18 and angled with respect to the wall front 16. The angle of the rear wall 22 with respect to the side walls gives each of the side walls 18 a trapezoidal shape. The fixing portion 14 projects from the central portion of the rear wall 22 and includes an upper wall 24 and a parallel lower wall 26 whose walls extend continuously from the upper and lower walls 20 of the portion 12 of the main body. The upper wall 24 includes a blind hole 28 located at the top and extending towards the rear wall 22 of the main body portion 12. The fixing portion 14 further includes the parallel side walls 30- perpendicular to the wall 24 above a hole 32 extending through the portion 14 between these side walls. The width W2 of the fixing portion 14 is smaller than the width W1 of the main body portion 12 and therefore the sections of the rear wall 22 of the main body portion are exposed on either side of the fixing portion 14 . Figure 2 shows a number of vehicles 34 comprising the support platforms 36, the rear trucks 40 and the front trucks 42. The trucks are equipped with the shock absorbers 10 and are supported for rolling movement on a rail 44. The front and rear trucks have many identical parts and the same reference numbers were used to identify parts common to both vehicles. As best seen in Figure 3, the trucks each comprise a body 46 to which the support wheel axles 48 are fixed to hold the support wheels 50 and to which the guide wheel shafts 52 for fixing the guide wheels 54 are fixed. Each truck 40 , 42 further includes separate parallel tabs 56 which depend on the undersides of the trucks to support the platforms 36. The tabs 56 of each truck are separated by a space 57 and each tab 56 includes various openings 58 aligned with the similar openings in the opposite tab 56 for receiving a pin 59 for fixing the support platforms to the truck. The tabs 56 include the front and rear ends 60 that do not come into contact with other trucks when the trucks are accumulated in a line. The. towing trolley 42 includes a fin 62 extending rearwardly of the upper portion of the body 46, and the forward trolley 40 includes a contact wall 64 in the upper portion of the body 46. The fin 62 and the contact wall 64 are the contact portions of the trucks, and these portions of the trucks are the ones that usually make contact when the vehicles are accumulated. The trolley bodies 46, which include the fin 62 and the contact wall 64, are made of metal and therefore a charge noise is generated when these portions of the trolleys collide. A shock absorber 10 is attached to the rear portion of each tow truck and the forward portion of each front truck by inserting the attachment portion 14 into the space 57 of the flanges 56 so that the hole 32 on the shock absorber is aligned with one of the openings 58 in the flanges 56. A bolt 66 is then passed through these aligned openings and secured to the flange 56 with a nut 68. The cushion is held in place by adjustment between the separate flanges as well as by the compression force of the combination of the bolt and the door. The axis 52 of the guide wheel that extends down into the space 57 is housed by the blind hole 28 in the upper wall 24 of the damper. The rear wall 22 of the cushion is at an angle complementary to the angle of the ends 60 so that the lower walls 20 and 26 of the shock absorber are aligned with the lower portion of the walls 56 so that the front wall 16 of the shock absorber remains generally perpendicular to the rail 44. The distance between the rear wall 22 and the front wall 16 of the damper is chosen so that when the dampers of the two adjacent trucks are at rest and in contact with each other, the flap 62 and the wall of the contact 64 are separated by a distance of about 1.27 cm (one-half inch), preferably about .635 cm (one-quarter inch), and ideally about .217 centimeters (one-eighth of an inch). This spacing is sufficient to prevent contact between the flap 62 and the wall 64 when a vehicle accumulates. Instead, when one vehicle makes contact with another, the wall 16 of the shock absorber 10 on the moving truck comes into contact with the wall 16 of the shock absorber 10 on the fixed truck and the shock absorbers are compressed by the force of the moving vehicle. until the wall 64 strikes the fin 62 to stop the vehicle. The impact of the urethane buffers on each other generates less noise than the impact of the metal against the metal since much of the impact energy is absorbed by the deformation of the urethane bodies instead of being converted to sound waves. The sound produced is also of a lower frequency and therefore is not as penetrating as the sound of the metal on the metal. The compression of the dampers absorbs a sufficient amount of energy so that when the flap 62 and the wall 64 finally meet, the wall 64 travels at a lower speed than it would have if the dampers were not there and consequently the impact produces a much softer sound After the impact, the urethane buffers return to their original form separating the fin 62 from the wall 64. The spacing between the fin and the wall, however, is very small, preferably of .217 centimeters (one-eighth of an inch). The eighth vehicle in the accumulation line where these dampers are used, for example, will only be 2.54 centimeters (one inch) out of place compared to the eighth vehicle in a vehicle line that does not include dampers. This small separation has no adverse effects on vehicle monitoring or system control. The present invention has been described in terms of a preferred embodiment, it being understood that numerous modifications of the shock absorber and the vehicle of the material will be apparent to those skilled in the art after reading and understanding the above description. For example, the shape of the shock absorber can be easily altered to allow it to be attached to a truck of a different design, and the shock absorbers can be fixed in other locations on the trucks and even on the vehicles without departing from the scope of this invention. It is intended that all such changes and modifications be included in this invention to the extent to which they are described by means of the various claims appended hereto.

Claims (19)

1. A conveyor system comprising a support rail, a first vehicle supported on said support rail by means of an advance truck, a tow truck, a second vehicle supported on said support rail in descending manner from the first vehicle by means of a wheelbarrow. Advancement and a haul truck, "wherein each of the haul trucks includes a front contact surface and a front non-contact surface and each such haul truck includes a rear contact surface and a non-contact surface. Subsequently, such a non-contact front surface of said second vehicle advance truck is separated from the rear non-contact surface of the first vehicle tow truck at a first distance when the front contact surface of the second vehicle is in contact with the rear contact surface of the first carret To drag the vehicle, the improvement is characterized in that it comprises: a front shock absorber connected to the second truck of the vehicle and having a front face separated forward of the front non-contact surface of the advance truck to a second distance; and a rear shock absorber connected to the first tow truck of the vehicle and having a rear face separated rearwardly from the rear non-contact surface of the tow truck at a third distance; where the sum of the second and third distance is greater than the first distance.

2. The conveyor system according to claim 1, characterized in that the sum is approximately 1.27 centimeters (one half inch) than the first distance given.

3. The conveyor system according to claim 1, characterized in that the sum is approximately 635 centimeters (one quarter of an inch) than the first distance given.

4. The conveyor system according to claim 1, characterized in that the sum is about .217 centimeters (one eighth of an inch) than the first given distance.

5. The conveyor according to claim 1, characterized in that the shock absorbers are elastic.

6. The conveyor according to claim 5, characterized in that the shock absorbers are urethane.

7. The conveyor according to claim 6, characterized in that each of the dampers includes a first face that conforms to a surface of the truck.

8. The conveyor according to claim 1, characterized in that the dampers can be compressed to allow contact between the second contact surface of the vehicle advance truck and the first contact surface of the vehicle haul truck when the second vehicle collides with the first vehicle.

9. The conveyor according to claim 1, characterized in that the front shock absorber comprises: a main body portion having an upper wall, a lower wall separated and parallel to the upper wall, first and second parallel side walls extending between upper wall and lower wall, a front wall connected between the side walls and the upper and lower walls, and a rear wall normal with respect to the side walls and angled with respect to the front wall; and a fastening portion having parallel upper and lower walls adjoining the upper wall and the lower wall of the main body portion, parallel spaced side walls extending between the upper and lower walls of the fixing portion and the wall of the main body portion and a hole extending through the fastening portion between the side walls.

10. The conveyor according to claim 9, characterized in that the front and rear shock absorbers are urethane.

11. A method for reducing the noise generated in a conveyor system by the accumulation of vehicles having contact and non-contact surfaces while maintaining a close separation between the contact surfaces of the vehicles, characterized in that it comprises the stage of mounting the dampers on the non-contact surfaces of the vehicles so that the contact surface of the adjacent vehicles makes contact only after the dampers make contact.

12. The method according to claim 11, characterized in that the step of mounting the dampers comprises the steps of inserting a portion of the damper into a space on an existing wheelbarrow and passing a bolt through an opening in said truck and an opening in such a portion.

13. A conveyor system comprising a support rail, and a first truck and a second truck supported on the support rail for movement therealong, wherein the trucks include each of at least one metal contact surface and at least one elastic contact surface arranged so that the metal contact surfaces of the first and second trucks contact each other only after the elastic contact surface of the second truck has made contact with the first truck.

14. The conveyor system according to claim 13, characterized in that the metal contact surfaces of the first and second trucks are coupled to each other only after the elastic contact surface of the second truck has made contact with the elastic contact surface of the second truck. the 'first wheelbarrow.

15. The conveyor according to claim 13, characterized in that the dampers can be mounted on existing trolleys.

16. In a conveyor system comprising: a support rail; a plurality of vehicles supported on the support rail for rolling movement along it, each of the vehicles includes a front and rear contact surface and a front and rear non-contact surface; an accumulation rail connected to the support rail for accumulating a plurality of vehicles in a closely spaced relationship; and a pusher for selectively pushing the vehicles on the accumulation rail; the improvement is characterized in that it comprises: dampers fixed to the non-contact surfaces to reduce the speed at which the contact surfaces of the adjacent vehicles make contact when the vehicles are accumulated, the dampers comprise: a main body portion having a first width, a front contact wall, and a rear wall separated and angled with respect to the front wall to engage the non-contact surfaces of the truck; and, a fixing portion formed integrally with the main body portion and having a second width smaller than the first width, parallel spaced apart side walls, and a hole connecting the side walls.

17. The conveyor system according to claim 16, characterized in that the vehicles comprise wheelbarrow portions and platform portions.

18. The conveyor system according to claim 17, characterized in that the contact surfaces are located on the truck portions.

19. The conveyor system according to claim 18, characterized in that the contact surfaces are located on the platform portions.