Conveyor with three plane locking system

Abstract: An improved combination carrier and stop assembly (10,11) is provided for use in automated conveyor assembly systems. The carrier (12) includes a reject pin (24) having two positions that flags defective workpieces and further confirms that non-defective workpieces have passed the previous quality checks. The carrier also includes an improved mechanism for being grasped and lifted by the stop assembly unit of the present invention thereby enabling the stop assembly unit to grasp and lift the carrier and workpiece above the forwardly moving conveyor (13). The stop assembly (11) detects the presence of a carrier (12), automatically checks the defective/non-defective status of the workpiece and thereafter grasps and lifts the carrier (12) and workpiece above the conveyor (13) if a task is to be performed. A programmable controller controls the moving parts of the stop assembly.

Description: This invention relates generally to conveyor systems for use in automated assembly systems. More specifically, this invention relates to conveyor systems for use in both synchronous and asynchronous assembly systems. The combination of the improved carrier and the improved precision stop assembly of the present invention enables the carrier to be stopped, grasped and lifted slightly by the stop assembly to enable an assembly task to be performed on the workpiece mounted on the carrier while enabling the conveyor to proceed forwardly underneath the carrier. The operation of the conveyor is not disrupted by the performance of the assembly task. BACKGROUND OF THE INVENTION Automated conveyor systems are well known. Automated conveyor systems presently used include synchronous assembly systems, asynchronous or non-synchronous assembly systems and machine tool loading systems. In a synchronous assembly system, a workpiece proceeds through each stage of the assembly process and does not proceed to the next stage until the remaining workpieces are ready to proceed to the next stage (i.e. each workpiece is in synch with the other workpieces). In synchronous assembly systems, the stage or task that takes the greatest amount of time will limit the rate at which all other tasks or stages can be completed because the other workpieces on the conveyor do not proceed to the next stage until all workpieces, including the workpiece at the slowest stage, are ready to proceed to the next stage. In asynchronous assembly systems, each assembly task is performed by physically removing the workpiece from the conveyor, performing the task and returning the workpiece to the conveyor where the workpiece is transported to the next stage. The conveyor in asynchronous assembly systems is always moving. However, workpieces are removed from the carrier so that slower tasks or stages do not necessarily slow down the optimum velocity of the conveyor. In the assembly of any multiple component part, some tasks take longer than others. If one task takes longer than the remaining steps, the longer step will limit the rate of production. To alleviate this problem, many systems include divide sections whereby the longer task is performed in multiple to keep at least one part with the longer task completed moving the down the conveyor at all times. In robotic systems, the preferred asynchronous assembly system includes a carrier for transporting the workpiece through the assembly system. When the carrier and workpiece reach an assembly point, a robotic arm or other mechanism lifts the carrier and workpiece above the conveyor system allowing the conveyor to proceed forward without the carrier and workpiece. If the task to be completed includes the application of a significant amount of force or pressure to the workpiece, it is often been necessary to have the robotic arm move the carrier and workpiece away from the conveyor. This movement requires time and additional hardware to accomplish. Thus, there is a need for a stop assembly, or work stop assembly, that will grasp the carrier, efficiently lift the carrier above the conveyor system and enable the assembly task to be performed to the workpiece directly above the conveyor system. Such a combination stop assembly and carrier system must provide support for the workpiece in all three planes, or the X, Y and Z planes. In addition to robotic machines performing more assembly functions, there is a movement toward automatic testing or gauging of workpieces as they are assembled or machined. Typically, a workpiece may be tested after every two or three assembly tasks are performed. After a workpiece is been determined to be defective, it must be removed from the assembly line or re-routed to a re-testing station or a repair station. Physically removing the carrier and workpiece from the conveyor system can be costly and time consuming. A better system would be to flag or otherwise mark the carrier in such a way so to indicate to stop assemblies downstream that the workpiece is defective and no task should be performed. Thus, there is a need for an improved combination carrier and stop assembly system that enables the carrier to be marked as one carrying a defective workpiece so that stop assemblies downstream from where the defect is detected do not waste time by performing additional assembly tasks (or processing or machining) on a defective workpiece. The "flagged" carrier may then be rerouted at the appropriate place downstream. Another problem not addressed by the prior art is the 90° turning requirements of many assembly lines. Linked conveyors or transport systems that can turn at 90° angles are known. However, many carrier units that rest on top of the moving conveyor cannot turn at 90° angles with short radiuses without getting jammed in the side walls of the conveyor support structure. Often, special tracks or special conveyor systems must be designed specifically for the 90° turns thereby adding to the cost of the entire assembly system. Thus, there is a need for a narrow carrier unit that will ride on top of a linked conveyor and that will further proceed through a 90° turn with a short radius without undue interference with the side walls of the conveyor system. BRIEF DESCRIPTION OF THE INVENTION The present invention makes a significant contribution to the art of automatic conveyor systems by providing an improved combination carrier and precision stop assembly for use in automatic conveyor systems. The combination includes two primary components: (1) an improved carrier; and (2) an improved stop assembly. The result is an conveyor system with higher transfer speeds and shorter index periods. The invention starts from the conveyor system shown in DE-A-40 10 697 which describes a conveyor which serves to convey carriers for workpieces on which work is to be performed, there being positioning and carrier-stopping means to halt and position each carrier on the conveyor so that the necessary work can be carried out on its respective workpiece. There is also a carrier-stopping unit which stops a carrier arriving at the unit for the purpose of exactly positioning a following carrier at the positioning and carrier-stopping means. In addition, means are provided for engaging and lifting opposing sides of a carrier, and it is on this prior document that the preambles of the independent claims 1, 7, 12, 14 and 18-22 are based. The advantages of the present invention are gained by the characterising features of those independent claims, while preferred features of the invention are set forth in the subsidiary claims. The carrier includes an upper surface for supporting a workpiece and a means for attaching the workpiece to the upper surface of the carrier. The under surface of the carrier rests on, and frictionally engages the moving conveyor. The front end of the carrier preferably includes a means for receiving an initial braking mechanism or stopping mechanism of the stop assembly. In the preferred embodiment, a slot is provided in the front end of the carrier to receive the initial braking mechanism of the stop assembly. The carrier may also be designed so that the front end of the carrier simply engages or bumps into the initial braking mechanism. After the carrier arrives at the stop assembly and is stopped by the initial braking mechanism, the carrier must be raised above the moving conveyor belt. The stop assembly includes means for engaging the opposing sides of the carrier and means for lifting the carrier above the conveyor. The carrier includes complimentary means for engaging the opposing sides of the stop assembly so that the carrier may be grasped and lifted by the stop assembly. In the preferred embodiment, the stop assembly includes a rod and piston, or a first projection, that is ejected from one side of the stop assembly and engages a hole, or a means for receiving the first projection, disposed in one side of the carrier. The rod engages the hole and drives the carrier toward the opposing side of the stop assembly. A slot, or means for receiving a second projection of the stop assembly, is provided in the carrier on the side opposite to the side including the hole. A complimentary wedge, or second projection, is provided in the stop assembly on the side of the stop assembly opposite to the location of the rod and piston. Thus, when the rod engages the hole and drives the carrier unit to the opposing side of the stop assembly, the slot in the carrier is mateably engaged over the wedge of the stop assembly. The above-mentioned rod and wedge of the stop assembly provide the means for grasping and lifting the carrier. The above-mentioned hole and slot of the carrier provide the means for engaging opposing sides of the stop assembly. In the preferred embodiment, the rod and the hole are tapered to compliment one another. Specifically, a conical hole and conical rod is an effective combination. The system is designed so that the engagement of the tapered, or conical rod in the tapered, or conical hole and the complimentary engagement of the elongated slot and elongated wedge act to raise the carrier slightly, approximately 0.010" above the moving conveyor. This slight lift of the carrier above the conveyor enables the conveyor to proceed in a forwardly direction without interference from the under side of the now stopped carrier. The preferred carrier includes at least two devices for activating sensors or proximity switches. A metal block or other detectable material is attached to one side toward the front end of the carrier for alerting a first sensor or proximity switch of the presence of the carrier at the stop assembly. A second sensor looks for the position of the reject pin mounted toward the rear end of the carrier. The reject pin includes at least two positions: a first position indicating that the workpiece is not defective; and a second position indicating that the workpiece is defective. The reject pin is preferably made of metallic substance or other substance that maybe easily detected by a sensor such as a proximity switch. The reject pin may take the form of a switch or other movable part with at least two positions, one position to indicate defects and another position to indicate no defects. Alternatively, sensors disposed on opposing sides of the carrier will detect at least three positions of a reject pin: far left, far right and center, thereby providing a reject pin capable of sending three signals to the programmable controller. The improved stop assembly in the present invention is a two-sided assembly disposed on both sides of the moving conveyor and may be mounted to the conveyor support. The stop assembly includes movable pistons and rods that are preferably driven by air pressure. A first movable piston and rod is the initial braking mechanism which extends outward and engages the front slot of the just-arriving carrier to stop it. At this point, the carrier is substantially stopped and the metal block on the carrier is detected by first sensor or proximity switch which alerts the programmable controller that the carrier has arrived at the stop assembly. The second sensor or proximity switch determines if the reject pin is in the position indicating that the workpiece is defective or in the position indicating that the workpiece is not defective. If the second proximity switch, or sensor, detects that the reject pin is in the position indicating that the workpiece is not defective, then the programmable controller a second piston and rod which engages the hole on one side of the carrier. The rod engages the hole and drives the carrier to the opposing of the stop assembly thereby engaging the slot in the opposing side of the carrier over the wedge of the opposing side of the stop assembly and lifting the carrier above the moving conveyor as noted above. In stop assemblies that perform quality tests and/or retests, a third and fourth piston and rod mechanisms are required. Specifically, if the stop assembly performs a quality test and workpieces determine to be defective, a piston and rod is required to drive the reject pin to the position indicating that the part is defective. Similarly, if the stop assembly is performing a re-test after a repair or simple re-test and the workpiece is determined to be not defective or no longer defective, another piston and rod may be required to drive the reject pin from the position indicating defect to the position indicating no defect. Thus, communication linkages are required between the programmable controller and the first sensor indicating the presence of the carrier, the second sensor indicating the position of the reject pin, the means for activating the initial braking mechanism, the means for activating the tapered or conical rod (first projection), the means for activating the reset piston/rod for resetting the reject pin position and the means for activating the reject piston/rod for activating the piston and rod that moves the reject pin from the non-defective to the defective position. Also included in the preferred embodiment of the carrier is an additional rear slot that enables the initial braking system to be activated before the carrier has completely departed from the stop assembly. The rear slot is disposed on the side of the carrier adjacent to the initial braking mechanism and extends rearward through the rear of the carrier. Because the rear slot is open ended at the rear end of the carrier, the initial braking mechanism may activated before the carrier has fully departed from the stop assembly and the initial braking mechanism will be accommodated in the rear slot but will not engage the carrier and will not stop the carrier from proceeding forward to the next stop assembly. The combination carrier and precision stop assembly lends itself to an improved method of performing an assembly task. A carrier resting on a moving conveyor arrives at a stop assembly. The carrier is stopped by initial braking mechanism and the presence of the carrier is thereafter detected by a first sensor. A signal from a second sensor initially detects whether the carrier is transporting a defective or non-defective workpiece. If the workpieces is non-defective, the stop assembly engages opposing sides of the carrier and lifts it above the conveyor. The programmable controller instructs the means for activating the piston and rod (first projection) to engage the hole (means for engaging the first projection) in the carrier which drives the carrier to the opposing side of the stop assembly where a slot (means for engaging the second projection) in the carrier positively engages the wedge (second projection) disposed on the opposing side of the stop assembly. This action raises the carrier above the moving conveyor enabling the conveyor to proceed forward without interference. At this point, the assembly task is performed on the non-defective workpiece. If the workpiece is defective, the rod does not engage the hole. Rather, the initial braking system is immediately released and the carrier, carrying the defective workpiece, proceeds to the next stop assembly which will either let the defective workpiece go through untouched, will reroute it, or conduct a repair task. In the preferred embodiment of the carrier, an arcuate relief or undercut is provided on the lower portion of each side. The undercut enables the carrier to proceed through a 90° or other sharp turn with a small radius. Specifically, the undercut accommodates the inner guide roller of the turn. This is an important development because the turning portion of the conveyor system is normally wasted conveyor space. It is difficult and expensive to construct the stop assembly unit on a turn or a portion of the conveyor that is not straight. Therefore, 90° turns are preferably made as quickly, or with a small a radius as possible. Thus, a carrier that can proceed unhindered through a 90° turn with a small radius is an important development. Another aspect of the shape of the carrier worth noting is the curvature of the front and rear ends of the carrier in combination with the curved undercuts provided in both sides of the carrier. The curvature of each end of the carrier enables a string of carriers lined up end-to-end to proceed around a sharp turn without interfering with the track support or otherwise hanging up in the middle of the turn. Carriers with straight sides and with squared-off ends cannot proceed around sharp turns and cannot proceed around turns lined up in an end-to-end fashion. It is therefore an object of the present invention to provide a carrier unit with an improved means for receiving an initial braking mechanism. Another object of the present invention is to provide a carrier unit that can be easily grasped and lifted above a moving conveyor. Yet another object of the present invention is to provide a carrier unit with an improved method of flagging defective parts and enabling the flag mechanism to be reset automatically. Another object of the present invention is to provide a carrier unit that is easily detected when it arrives at a stop assembly. Another object of the present invention is to provide a carrier unit configured to pass through sharp turns in an assembly line and further to pass through sharp turns in an assembly line without interfering with the carrier unit abutting the front or rear end of the carrier unit. Another object of the present invention is to provide a stop assembly with an improved method of grasping and raising a carrier and workpiece above the moving conveyor and thereafter providing support for the carrier and workpiece in the X, Y and Z planes. Yet another object of the present invention is to provide a stop assembly with an improved system for detecting and flagging defective workpieces. Yet another object of the present invention is to provide an improved stop assembly for retesting and/or repairing defective workpieces and resetting the flag mechanism indicating that the workpiece is defective. It is still another object of the present invention to provide an improved carrier unit that may proceed through a 90° turn with a small radius. BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated more or less diagrammatically in the accompanying drawings, wherein: Figure 1 is a top plan view of a carrier in a stop assembly and a carrier leaving the same stop assembly, both the carriers and stop assembly being made in accordance with the preferred embodiments of the present invention; Figure 2 is a right-side view of the stop assembly and carriers shown in Figure 1; Figure 3 is a left-side view of the stop assembly and carriers shown in Figure 1; Figure 4 is a sectional view taken substantially along line 4-4 of Figure 1 particularly illustrating the initial braking mechanism; Figure 5 is a sectional view taken substantially along line 5-5 of Figure 1; Figure 6 is a sectional view taken substantially along line 5-5 of Figure 1 particularly illustrating the carrier as it is grasped and lifted above the carrier by the stop assembly; Figure 7 is a sectional view taken substantially along line 7-7 of Figure 1; Figure 8 is a top view of a carrier shown in Figure 1; Figure 9 is rear-end view of a carrier shown in Figure 1; Figure 10 is a right-side view of a carrier shown in Figure 1; Figure 11 is a left-side view of a carrier shown in Figure 1; Figure 12 is a top view of the wedge of the stop assembly shown in Figure 1; Figure 13 is a right-side view of the wedge shown in Figure 12; Figure 14 is a front-end view of the wedge shown in Figure 12; Figure 15 is a rear-end view of the wedge shown in Figure 12; Figure 16 is a top plan view of a 90° turn particularly illustrating the movement of two carriers made in accordance with the present invention proceeding through the turn; and Figure 17 is an end view of the 90° turn and a carrier shown in Figure 16. DETAILED DESCRIPTION OF THE INVENTION Like reference numerals will be used to referred to like or similar parts from Figure to Figure in the following description of the drawings. Referring first to Figure 1, a combination carrier/stop assembly 10 is shown including the stop assembly 11 and two carriers 12, one having just entered the stop assembly 11 and the other just departing the stop assembly 11. The direction of travel of both the carriers 12 and the conveyor, indicated generally at 13, is indicated by the direction arrow 14. The conveyor 13 is disposed within a track support, indicated generally at 15. The stop assembly 11 is disposed on either side of the conveyor 13. Figure 1 also illustrates the two sensors 16, 17. Sensor 16 (or proximity switch 16) senses the arrival of the carrier 12 at the stop assembly by sensing the presence of a metal block 18 (see Figure 3) on the left side 21 of the carrier 12 (the right side of the carrier 12 being designated as 22). The stop assembly 11 includes a means for communicating the signal of the sensor 16 from the sensor 16 to the programmable controller (not shown). Upon receiving the indication that the carrier 12 has arrived at the stop assembly 11, the programmable controller reads the incoming signal from the sensor 17. The sensor 17 indicates the position of the head 23 of the reject pin, indicated generally at 24. When the head 23 of the reject pin 24 is disposed toward the right side 22 of the carrier 12, the workpiece (not shown) is indicated to be non-defective, or the workpiece has passed the last quality check. If the head 23 of the reject pin 24 is disposed inward so that the groove 25 is disposed under the hole 20 where groove 26 is shown in Figure 1, then the workpiece is indicated to be defective and the prescribed task to be performed at the stop assembly 11 is not carried out. In the embodiment shown in the Figures and described herein, if the sensor 17 detects the presence of the head 23 of the reject pin 24, the workpiece is deemed non-defective. If the sensor 17 cannot detect the presence of the head 23 because it is disposed to the left of the sensor 17, then the part is deemed defective. Of course, an opposite configuration could be employed and still fall within the scope of the invention. As seen in Figure 1, the head 23 of the reject pin 24 is disposed toward the right near the sensor 17 (or proximity switch 17) and the sensor 17 sends a signal to the programmable controller that the workpiece is not defective and the prescribed assembly task will be carried out. The hole 29 disposed toward the center of the carrier 12 is intended to provide a means for affixing the workpiece (not shown) to upper surface 30 of the carrier 12. Of course, other suitable means for affixing a workpiece to the carrier 12 are available. Turning to Figure 2, a right side view of the stop assembly 11 and a carrier 12 is shown. Referring first to the carrier 12 shown to the right of the stop assembly 11, the front slot 27 and rear slot 28 are illustrated. The front slot 27 is intended to receive or provide a means for receiving an initial braking mechanism or initial braking rod 31 (see Figure 4) of the stop assembly 11. Essentially, the front slot 27 is the area of first contact between the carrier 12 and the stop assembly 11. The rear slot 28 is also intended to accommodate the initial braking rod 31 (see Figure 4) in the event the initial braking rod 31 extends outward prematurely as the carrier 12 leaves the stop assembly 11 or if the system is simply timed so that the initial braking rod 31 is intended to extend outward before the carrier 12 has completely departed from the stop assembly 11. The rod 31 can extend into the slot 28 and the carrier can still pass forward (to the right) without interference because the rear end 32 of the rear slot 28 is open and allows the rod 31 to pass through. Referring to Figure 4, the means for activating the initial braking rod 31 includes a piston 34 and rod 31 disposed within a cylinder 41, and a supply of pressurized air (not shown), communication between the air supply and clinger 41 is provided by the port 35. The air supply is controlled by the programmable controller (not shown). Returning to Figure 2, the hole 33 disposed toward the center of the right side 22 of the carrier 12 accommodates a rod 36 (not shown in Figure 2; see Figures 5 and 6). Turning now to Figures 5 and 6, the rod 36 and piston 37 are moved inward and outward via air or fluid pressure in the cylinder 78. Communication between the cylinder 78 and a pressurized air supply (not shown) is established through the port 38. As noted below, when the rod 36 engages the hole 33, the carrier 12 is moved toward the left (according to the orientation of Figure 1) and the slot 39 (see Figure 3) engages a wedge 42 (see Figure 7) which results in the lifting of the carrier 12 (see Figure 6). Referring to Figures 2 and 7, the reject piston 43 and rod 64 move the reject pin 24 toward to the position indicating that the workpiece 45 is defective. Communication is established between the cylinder 50 and the pressurized air supply (not shown) by the port 44. Also seen in Figure 2 is a view of the head 23 of the reject pin 24. The head 23 being disposed along the right side 22 of the carrier 12 thereby enabling it to be sensed by the sensor 17 (see Figure 1). Also shown in Figure 2 is a side view of the undercut 46 disposed on the right side 22 of the carrier 12 (see also Figure 8). A like undercut 47 is disposed on the left side 21 of the carrier 12 as seen in Figure 8. Turning to Figure 3, a left side view of the stop assembly 11 and carrier 12 is shown. As discussed above, the presence of the carrier 12 and the stop assembly 11 is sensed by a sensor 16 (see Figure 1) which detects the presence of the metal block 18 disposed on the left side 21 of the carrier 12. Also disposed on the left side 21 of the carrier 12 is the distal end 48 of the reject pin 24. As noted above, if the particular stop assembly 11 shown were a testing and/or repair station, it is foreseeable that a defect in the workpiece 45 could be corrected and/or repaired. In this event, the reject pin 24 would to be reset to the position indicating that the workpiece 45 is not defective. To accomplish this end, a piston 49 and rod 51 (see Figure 7) are provided to drive the distal end 48 of the reject pin 24 back to the position indicating that the workpiece 45 is not defective (see also Figure 7). Also to be noted on the left side 21 of the carrier 12 is the elongated slot 39 which engages the wedge 42 (see Figure 4) when the carrier 12 is grasped and lifted by the stop assembly 11. As noted above, the undercut 47 is to facilitate the maneuvering of the carrier 12 around a 90° turn. The port 52 provides fluid communication between the piston 49 and the pressurized air supply (not shown). The metal block 18 may be a strip of metal as opposed to a block of metal if the sole function of the block 18 is to be detected by the sensor 16. However, in the preferred embodiment, the block 18 also acts to engage a comb-like structure with teeth (not shown) that engage each end 18a, 18b of the block 18. The comb-like structure engages a group of carriers 12 by the blocks 18 and shuttles the carriers 12 forward together to a succeeding station. The sectional view provided in Figure 4 illustrates the action of the wedge 42 in the slot 39 and the action of the initial braking rod 31 in the front slot 27. Also to be noted from Figure 4 is the proximity of the metal block 18 to the first sensor 16 as the carrier 12 enters the stop assembly 11. The track support 15 includes mounting slots 19 for attaching the stop assembly 11 to the track support 15. As noted above, shortly after carrier 12 leaves the stop assembly 11, or during the departure of a carrier 12 from a stop assembly 11, the means for activating the initial braking mechanism 31 or the rod 31 is activated. The distal end 53 of rod 31 also initially engages the slot 27 as a carrier 12 enters the stop assembly 11. The means for activating the rod 31 and piston 34 is pressurized air that is supplied through the port 35 to the cylinder 41 to drive the piston 34 and rod 31 in the direction of the arrow 54 to the position shown in phantom in Figure 4. Quad-rings indicated at 55, 56, 57 and 58 provide a seal and prevent escape of air pressure. The initial braking rod 31 is released or moved to the right upon the application of pressurized air through the port 61 thereby driving the piston 34 to the right and into the retracted position shown in solid in Figure 4. As noted above, the sensor 16 is in position to detect the proximity of the metal block 18. And as shown in Figure 7, the sensor 17 is in position to detect the proximity of the head 23 of the reject pin 24. The track support extrusion 15 supports a liner 62 which in turn supports a standard conveyor indicated generally at 13. The conveyor 13 employed in the preferred embodiment is sold under the name "Rex 1700" and is claimed in U.S. Patent No. 4,436,200. Figure 7 illustrates the operation of the flag rod 64 and piston 43 and the reset rod 51 and piston 49. Air is supplied to the cylinder 50 through the port 44 which in turn drives the piston 43 and the rod 64 to the left to engage the head 23 of the reject pin 24. This action would move the slot 26 off the ball detent 65 and move the slot 25 over on top of the ball detent 65. This position would indicate that the workpiece 45 (see Figure 2) is defective and that any prescribed task should not be performed on the workpiece 45. The rod 64 is withdrawn upon the application of pressurized air through the port 66 and through the cylinder 50 thereby driving the piston 43 back to the position shown in Figure 7. Quad-rings 67, 68, 69 and 70 prevent air leakage and help ensure effective operation of the piston 43. Turning to the reset piston 49 also shown in Figure 7, pressurized air is supplied through the port 52 which drives the rod 51 to the right to reset the reject pin 24 from the position indicating that the workpiece 45 is defective to the position indicating that the workpiece 45 is not defective. The rod 51 is withdrawn upon the application of pressurized air through the port 73 which drives the piston 49 to the left. Quad-rings 74, 75, 76 and 77 prevent air leakage. Returning to Figures 5 and 6, the grasping and lifting of the carrier 12 by the stop assembly 11 is illustrated. After the carrier 12 has arrived at the stop assembly 11 and the presence is indicated by detection of the metal block 18 by the sensor 16, the programmable controller verifies that the workpiece 45 is not defective by reading the signal from the sensor 17. Upon confirmation that the workpiece 45 is not defective (as indicated by the position of the reject pin 24 in Figures 1 and 7), a signal is sent to the means for activating the piston 37 and rod 36. Pressurized air is supplied through the port 38 to the cylinder 78 which drives the piston 37 and tapered rod 36 to the left as seen in Figure 6. The engagement of the distal end 81 of the rod 36 in the tapered hole 33 drives the carrier 12 to the left as shown in Figure 6. This action causes the slot 39 to fully engage the wedge 42 thereby lifting the carrier 12 above the conveyor 13. This action will be noted by the slight gap between the underside 82 of the carrier 12 and the upper surface 83 of the conveyor link 13 shown in Figure 6. Quad-rings 84, 85, 86 and 87 prevent air leakage and provide effective operation of the piston 37. Pressurized air is supplied through the port 40 to retract the rod 36 and piston 37. The sequence of operation of the carrier 12 through the stop assembly 11 is illustrated by viewing Figures 4 through 7. In Figure 4, the carrier 12 has just arrived at the stop assembly 11 and the front slot 27 has been engaged by the distal end 53 of the initial braking rod 31 as shown in phantom. The under surface 82 of the carrier 12 is still resting on the upper surface 83 of the conveyor. The slot 39 is not positively engaged by the wedge 42 but a gap between the lower angled surface 92 of the wedge 42 and the lower angled surface 93 of the slot 39 is evident. The presence of the carrier 12 has been detected by the sensor 16 and the information has been sent to the programmable controller which has now received the signal from the sensor 17 indicating that the workpiece is not defective. A signal is sent from the programmable controller to the means for activating the piston 37 and rod 36 to provide pressurized air through the port 38 to the cylinder 78 to drive the piston 37 and consequently the tapered rod 36 into the tapered hole 33 (see Figure 5). As seen in Figure 6, the rod 36 engages the hole 33 and drives the carrier 12 to the left side of the stop assembly 11. This action causes the slot 39 to positively engage the wedge 42 thereby creating the gap between the under surface 82 of the carrier 12 and the upper surface 83 of the conveyor link 13 (see Figure 6). The carrier 12, as shown in Figure 6, is in the position whereby the conveyor 13 is free to move underneath the carrier 12 without interference and an assembly task may be performed on the workpiece 45. Rods 36 and 31 are subsequently retracted to lower the carrier 12 and allow it to depart from the stop assembly 11. Figures 8 through 11 illustrate physical details of the preferred embodiment of the carrier 12. Of course, alternative embodiments will be readily ascertainable by those skilled in the art without departing from the scope of the present invention. Turning to Figure 8, a top view of the carrier 12 illustrates the undercuts 46, 47 for turning around right and left turns respectively. The front end 72 and the rear end 71 are curved to enable of group of carriers 12 to proceed through a sharp turn with jamming. If the ends 72, 71 are not curved and instead are square, the ends 72, 71 of each carrier 12 would engage one another thereby causing the carriers 12 to jam in the turn. The hole 29 provides a means for mounting the workpiece 45 but it will be understood that other mounting means are readily available. The reject pin 24 is in the position indicating that the workpiece is not defective. Figure 8 also illustrates the open end 32 of the rear slot 28 which enables the initial braking rod 31 to be activated before the carrier 12 completely departs from the stop assembly 11. Figure 9 illustrated the two positions of the reject pin 24. As previously discussed in reference to Figure 1, when the groove 26 is disposed on top of the ball detent 65, the workpiece 45 is deemed not defective. When the groove 25 is disposed over the ball detent 65, the workpiece 45 is deemed defective because the second sensor 17 does not detect the presence of the head 23 of the reject pin 24 (see Figure 1). Of course, the defective and non-defective positions could be reversed and the flag mechanism could be embodied in a switch (or other multiple position part) other than the reject piston 24 without departing from the scope of the present invention. As noted above, more than two signals (defective/non-defective) may be obtained from the disclosed reject pin 24 concept. For example, two sensors disposed on opposing sides of the carrier could detect three positions of the reject pin (far left, far right and middle). Figure 10 and 11 illustrate the tapered hole 33/elongated slot 39 combination of the preferred embodiment. It will be noted that any combination that provides support for the carrier 12 in the X, Y and Z planes would be suitable for the purposes of the present invention. Figures 10 and 11 also include phantom views of the rods 64, 36 and 31 of the stop assembly 11. Figure 12 is an illustration of the wedge 42 disposed on the left side of the stop assembly 11. The front end 94 is tapered to the left thereby providing an easier opening to accommodate a carrier 12. Figures 16 and 17 illustrate the ability of the carrier 12 of the present invention to make a 90° turn with a short radius 100. The conveyor track 13 is a standard conveyor consisting of relatively small links pivotally connected together that enable the conveyor to turn around sharp corners as the one indicated in Figure 16. A guide roller 101 guides the conveyor around the turn. The guide roller 101 does not provide a driving mechanism for the carriers 12 in addition to the driving mechanism for the conveyor 13. The arcuate undercut 47 enables the carrier 12 to turn about the inner edge 102 of the track support 15. To accommodate the sharp turn illustrated in Figure 16, a standard conveyor linkage 13 is utilized with indentations indicated at 103 and 104 to accommodate the guide roller 101. Thus, while it has been possible before to provide a conveyor 13 that could turn 90° at a radius 100, the present invention provides a carrier 12 that can make a sharp turn without undue modification of the carrier 12 or the track support 15. Thus, the present invention provides an improved carrier for transporting workpieces between stop assembly stations. The carrier provides an improved method for flagging defective workpieces and an improved method of resetting the defect flag. The stop assembly of the present invention provides an improved method for sensing the presence of the carrier, the defective/non-defective status of the workpiece and for grasping and lifting the carrier just above the moving conveyor to allow the conveyor to continue forward as a prescribed assembly task, test or repair is conducted on the workpiece. The configuration of the carrier also enables it to turn sharp corners without interfering with a standard track support. Although only one preferred embodiment of the present invention has been illustrated and described, it will at once be apparent to those skilled in the art that variations may be made within the spirit and scope of the invention. Accordingly, it is intended that the scope of the invention be limited solely by the scope of the hereafter appended claims and not by any specific wording in the foregoing description.

Claims: A combination carrier and precision stop assembly (10, 11) for use in a conveyor system, the combination comprising a carrier (12), a stop assembly (11), and means for engaging and lifting opposing sides of the carrier (12), the carrier having an upper surface (30) for supporting a workpiece, an under surface for frictionally engaging a moving conveyor (13), and means for engaging one side of the stop assembly, there also being means for engaging a second opposing side of the stop assembly, whereby the carrier (12) is raised vertically upon engagement of the two opposing sides of the stop assembly (11) so as to allow the conveyor (13) to move forwards underneath the carrier without frictionally engaging the under surface of the carrier; and characterised in that the stop assembly (11) includes an initial braking mechanism (31) and means for activating the initial braking system to initially stop the carrier upon arrival at the stop assembly. The combination of claim 1, wherein the carrier (12) also includes means for receiving the initial braking mechanism (31) to initially stop the carrier upon arrival at the stop assembly. The combination of claim 1 or claim 2, wherein the stop assembly (11) includes a first sensor (16) for detecting the presence of the carrier (12) after the carrier is initially stopped by the initial braking mechanism (31), the stop assembly also including means for communicating the presence of the carrier (12) to a programmable controller upon arrival of the carrier (12) at the stop assembly. The combination of any one of claims 1-3, wherein the carrier (12) also includes a reject pin (24) disposed in the carrier (12) and having at least two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective. The combination of claim 4, wherein the stop assembly (11) includes a second sensor (17) for detecting the position of the reject pin (24) as well as means for communicating the position of the reject pin (24) to a programmable controller, the programmable controller activating the means for engaging and lifting opposing sides of the carrier only when the reject pin is in the position indicating the workpiece is not defective. The combination of claim 4 or claim 5, wherein the stop assembly (11) includes a reset piston (34) and means for activating the reset piston, and wherein a programmable controller activates the means for activating the reset piston, the reset piston thereafter engaging the reject pin (24) and moving the reject pin from the position indicating that the workpiece is defective to the position indicating the workpiece is not defective. A carrier (12) for use in a conveyor system wherein means are provided for engaging and lifting opposing sides of the carrier, the carrier (12) having an upper surface (30) for supporting a workpiece and an under surface for frictionally engaging a moving conveyor (13), there also being means for engaging one side of a stop assembly (11) and means for engaging a second opposing side of the stop assembly, characterised in that a reject pin (24) is disposed in the carrier (12), the reject pin having two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective. The carrier of claim 7, including means for receiving an initial braking mechanism (31) to initially stop the carrier (12) upon arrival at the stop assembly (11). The carrier of claim 7 or claim 8, wherein the carrier (12) has a front end, a rear end, a middle portion and two sides, and wherein at least one side includes an arcuate undercut (46) for accommodating a turn in the conveyor system, the front end and rear end including curved vertical surfaces to prevent interference with preceding and succeeding carriers. The carrier of claim 8, wherein one side of the carrier (12) includes a metallic block (18) capable of detection by a proximity sensor (16). The carrier of claim 9 or claim 10, wherein at least one side toward the rear end includes a rear slot (28), the rear slot extending rearwards out the rear end and accommodating the initial braking mechanism (31), thereby enabling the initial braking system to be activated in anticipation of a succeeding carrier (12) before the carrier fully departs from the stop assembly (11). A stop assembly (11) for stopping and receiving carrier units (12) of a moving conveyor assembly system, the stop assembly comprising means for engaging and lifting opposing sides of the carrier units, and the carrier units each having an upper surface (30) for supporting a workpiece, an under surface for frictionally engaging a moving conveyor (13), and means for engaging one side of the stop assembly, there also being means for engaging a second opposing side of the stop assembly, characterised by: (a) an initial braking mechanism (31) and means for activating the initial braking system to initially stop a carrier (12) upon arrival at the stop assembly (11); (b) a first sensor (16) for detecting the presence of the carrier (12) and means for communicating the presence of the carrier to a programmable controller; and (c) a second sensor (17) for detecting a position of a reject pin (24) disposed on the carrier and means for communicating the position of the reject pin to a programmable controller, the carrier unit (12) being vertically raised upon engagement of the opposing sides of the carrier to allow the conveyor (123) to move forwards underneath the carrier (12) without frictionally engaging an under surface of the carrier. The stop assembly of claim 12, wherein the first sensor (16) detects the departure of the carrier (12) from the stop assembly (11), and the stop assembly further includes means for communicating the departure of the carrier to the programmable controller, the programmable controller instituting activation of the initial braking mechanism (31) to initially stop a succeeding carrier (12). A method of operating an automatic conveyor-type assembly system wherein opposing sides of a carrier are engaged and lifted, the system comprising a carrier (12), a stop assembly (11), and means for engaging and lifting opposing sides of the carrier (12), the carrier having an upper surface (30) for supporting a workpiece, an under surface for frictionally engaging a moving conveyor (13), and means for engaging one side of the stop assembly, there also being means for engaging a second opposing side of the stop assembly, which method comprises transporting a carrier (12) resting on the conveyor (13) in a direction towards the stop assembly (11), and engaging a front portion of the carrier (12) with a braking mechanism (31) extending outwards from the stop assembly (11), characterised in that the method further comprises : (a) sensing a presence of the carrier (12) at the stop assembly (11) with a first sensor (16) and communicating the presence of the carrier to a programmable controller, (b) sensing a position of a reject pin (24) disposed on the carrier (12) with a second sensor (17) disposed on the stop assembly (11), the reject pin having two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective, (c) communicating the position of the reject pin (24) to the programmable controller, (d) in the event that the position of the reject pin (24) indicates the workpiece is not defective, the programmable controller activating means engaging opposing sides of the carrier, the carrier unit being vertically raised upon engagement of the opposing sides of the carrier and allowing the conveyor (13) to move forwards underneath the carrier without frictionally engaging an under surface of the carrier, (e) performing a prescribed task to the workpiece, (f) deactivating the means for activating the means for engaging opposing sides of the carrier, (g) deactivating the means for activating the initial braking mechanism (31), thereby releasing the initial braking mechanism and permitting the carrier (12) to move forwardly through the stop assembly (11), (h) in the event that the position of the reject pin (24) indicates the workpiece is defective, the programmable controller deactivating the means for activating the initial braking mechanism (31), thereby releasing the initial braking system and permitting the carrier (12) to move forwardly through the stop assembly (11) without any task being performed on the defective workpiece, and (i) activating the means for activating the initial braking mechanism (31), thereby readying the stop assembly (11) for a succeeding carrier. The method of claim 14, wherein the carrier (12) includes a rear slot (28) which extends out a rear end of the carrier, the rear slot accommodating the initial braking mechanism (31), thereby enabling the initial braking system to be activated in anticipation of the succeeding carrier before the carrier fully departs from the stop assembly. The method of claim 14 or claim 15 wherein, after the prescribed task is performed, the workpiece is tested by means for testing the workpiece, the means for testing the workpiece communicating a result signal to the programmable controller, which result signal may indicate that the workpiece is defective or may indicate that the workpiece is not defective, and, in the event that the result signal indicates the workpiece is defective, the programmable controller sending a signal to activate means for activating a reject piston (34) thereby extending the reject piston outwards to engage the reject pin (24) on the carrier and move the reject pin from the position indicating the workpiece is not defective to the position indicating the workpiece is defective. The method of claim 16, wherein, in the event the result signal indicates that the workpiece is defective, the programmable controller sending a repair signal to means for repairing the defective workpiece, the means for repairing the defective workpiece completing a repair task on the defective workpiece, the workpiece being re-tested by the means for testing the workpiece, the means for testing the workpiece communicating a result signal to the programmable controller, which result signal may indicate that the workpiece is defective or may indicate that the workpiece is not defective, and, in the event that the result signal indicates the workpiece is no longer defective, the programmable controller sending a signal to activate the means for activating a reset piston, thereby extending the reset piston outwards to engage the reject pin on the carrier and move the reject pin from the position indicating the workpiece is defective to the position indicating the workpiece is not defective. A combination carrier and precision stop assembly (10, 11) for use in a conveyor system, the combination comprising a carrier (12), a stop assembly (11), and means for engaging and lifting opposing sides of the carrier, the carrier having an upper surface (30) for supporting a workpiece and an under surface for frictionally engaging a moving conveyor (13), there being means for receiving a braking mechanism (31) to initially stop the carrier upon arrival at the stop assembly, wherein means are provided for engaging a first projection of the stop assembly (11) and means are provided for engaging a second projection of the stop assembly, the means for engaging the first and second projections of the stop assembly being disposed on opposing sides of the carrier so that engagement of the first projection forces positive engagement of the second projection, the carrier being vertically raised upon engagement of the first and second projections to allow the conveyor (13) to move forwards underneath the carrier (12) without frictionally engaging the under surface of the carrier, characterised in that the stop assembly (11) includes the braking mechanism (31) and means for activating the braking system to initially stop the carrier upon arrival at the stop assembly, as well as the first projection, means for activating the first projection, and the second projection. A carrier (12) for use in a conveyor system which includes means for engaging and lifting opposing sides of the carrier, the carrier (12) comprising an upper surface (30) for supporting a workpiece and an under surface for frictionally engaging a moving conveyor (13), and means for receiving an initial braking mechanism (31) to initially stop the carrier upon arrival at the stop assembly (11), characterised in that the carrier (12) includes means for engaging a first projection and means for engaging a second projection, there also being a reject pin (24) in the carrier (12), the reject pin having two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective. A stop assembly (11) for stopping and receiving carrier units (12) of a moving conveyor assembly system wherein means are provided for engaging and lifting opposing sides of the carrier units, and the carrier units each having an upper surface (30) for supporting a workpiece, an under surface for frictionally engaging a moving conveyor (13), and means for engaging one side of the stop assembly, there also being means for engaging a second opposing side of the stop assembly, characterised in that the stop assembly (11) comprises: (a) an initial braking mechanism (31)and means for activating the initial braking system to initially stop a carrier upon arrival at the stop assembly, (b) a first sensor (16) for detecting the presence of the carrier, and means for communicating the presence of the carrier to a programmable controller, (c) a second sensor (17) for detecting a position of a reject pin (24) disposed on the carrier (12), and means for communicating the position of the reject pin to a programmable controller, and (d) a first projection and means for activating the first projection, the first projection mateably engaging means for receiving the first projection disposed on a carrier, a second projection for engaging means for engaging the second projection disposed on the carrier, the second projection and first projection being disposed on opposing sides of the carrier so that engagement of the first projection in the means for engaging the first projection forces positive engagement of the second projection in the means for engaging the second projection, the carrier unit (12) being vertically raised upon engagement of the first projection and second projection to allow the conveyor (13) to move forwards underneath the carrier without frictionally engaging an under surface of the carrier. A method of operating an automatic conveyor-type assembly system wherein opposing sides of a carrier (12) are engaged and lifted, the system comprising a carrier (12), a stop assembly (11), and means for engaging and lifting opposing sides of the carrier (12), the carrier having an upper surface (30) for supporting a workpiece, an under surface for frictionally engaging a moving conveyor (13), and means for engaging one side of the stop assembly, there also being means for engaging a second opposing side of the stop assembly, which method comprises transporting a carrier (12) resting on the conveyor (13) in a direction towards the stop assembly (11), and engaging a front portion of the carrier (12) with a braking mechanism (31) extending outwards from the stop assembly (11), characterised in that the method further comprises : (a) sensing the presence of the carrier at the stop assembly with a first sensor (16) and communicating the presence of the carrier to a programmable controller, (b) sensing a position of a reject pin (24) disposed on the carrier with a second sensor (17) disposed on the stop assembly (11), the reject pin having two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective, (c) communicating the position of the reject pin (24) to the programmable controller, and, in the event the position of the reject pin indicates the workpiece is not defective, the programmable controller activating means for activating a first projection on a first side of the stop assembly, the first projection thereafter mateably engaging means for engaging the first projection disposed on a carrier unit, the engagement of the first projection in the hole forcibly engaging means for engaging a second projection disposed on the carrier with a second projection disposed on a second, opposing side of the stop assembly, the engagement of the first projection on one side of the carrier forcing positive engagement of the second projection on an opposing side of the carrier, the carrier unit being vertically raised upon engagement of the first projection and second projection in the hole and slot respectively and allowing the conveyor (13) to move forwards underneath the carrier (12) without frictionally engaging the under surface of the carrier, (d) performing a prescribed task to the workpiece, (e) deactivating the means for activating the first projection, thereby releasing the first projection from the means for engaging the first projection, (f) deactivating the means for activating the initial braking mechanism (31), thereby releasing the initial braking mechanism and permitting the carrier to move forwardly through the stop assembly (11), (g) in the event the position of the reject pin indicates the workpiece is defective, the programmable controller deactivating the means for activating the initial braking mechanism (31), thereby releasing the initial braking system and permitting the carrier to move forwardly through the stop assembly (11) without any task being performed on the defective workpiece, and (h) activating the means for activating the initial braking mechanism (31), thereby readying the stop assembly (11) for a succeeding carrier. A method of operating an automatic conveyor-type assembly system using a carrier (12), a stop assembly (11) and a programmable controller, wherein opposing sides of the carrier are engaged and lifted, and the carrier (12) comprises an upper surface (30) for supporting a workpiece and an under surface for frictionally engaging a moving conveyor (13), there being means for receiving a braking mechanism (31) to initially stop the carrier upon arrival at the stop assembly (11), means for engaging a first projection, and means for engaging a second projection, and a reject pin (24) disposed in the carrier, the reject pin having two positions, one position indicating that the workpiece is defective, and another position indicating the workpiece is not defective, and wherein the stop assembly (11) includes an initial braking mechanism (31) and means for activating the initial braking system to initially stop a carrier upon arrival at the stop assembly, a first sensor (16) for detecting the presence of the carrier, means for communicating the presence of the carrier to a programmable controller, a second sensor (17) for detecting the position of a reject pin (24) disposed on the carrier, means for communicating the position of the reject pin to a programmable controller, a first projection and means for activating the first projection, the first projection mateably engaging the means for engaging the first projection disposed on the carrier unit, a second projection for engaging the means for engaging the second projection disposed on the carrier, the second projection and first projection being disposed on opposing sides of the carrier so that engagement of the first projection forces positive engagement of the second projection, the carrier unit being vertically raised upon engagement of the first projection and second projection to allow the conveyor to move forwards underneath the carrier (12) without frictionally engaging an under surface of the carrier, which method comprises: (a) transporting the carrier (12) on a forwardly-moving conveyor (13) until the means for receiving the initial braking system (31) engages the initial braking system; (b) sensing the presence of the carrier with the first sensor (16) and communicating the presence of the carrier to the programmable controller; (c) sensing the position of the reject pin (24) and communicating the position of the reject pin to the programmable controller; (d) in the event the position of the reject pin indicates that the workpiece is defective, the programmable controller performing step i; (e) in the event the position of the reject pin indicates the workpiece is not defective, the programmable controller performing step f; (f) activating means for activating the first projection to engage the means for engaging the first projection which forces the second projection to engage the means for engaging the second projection; (g) performing a prescribed task on the workpiece; (h) deactivating means for activating the first projection to remove the first projection from the means for engaging the first projection and consequently removing the second projection from the means for engaging the second projection; (i)) deactivating the means for activating the initial braking mechanism (31), thereby enabling the carrier and workpiece to depart the stop assembly; and (j) activating the means for activating the initial braking mechanism (31) to extend the initial braking mechanism outwardly to thereby stop a succeeding carrier.

Inventors: WESKAMP ROBERT, WESKAMP, ROBERT
Applicants: WESKAMP ROBERT, WESKAMP, ROBERT
Application year: 1993
Main classification: B65G49
IPC codes: B23P21, B23Q1, B65G35, B65G47, B23P19, B23Q7, B65G17