Oven Chain Measurement System

Abstract

A chain tensioning sprocket is moveable with a predetermined force into a U-shaped path of a chain to apply continuous tensioning force to the chain. The change in length of the chain is measured by detecting the movement of the chain tensioning sprocket into the U-shaped path of the chain, and measurement of movement of the chain tensioning sprocket indicates a change in the length of the whole chain, which, in turn, indicates the wear on the parts of the chain and the expected operative life of the chain.

Claims

1. Apparatus for detecting the deterioration of a continuous conveyor link chain extending along a path through a tunnel oven due to wear of the links of the chain, comprising: a rotary drive sprocket for moving the chain along its length through the continuous path through the tunnel oven, a rotary chain tensioning sprocket for guiding the chain along the continuous path, a chain tensioning device for moving the rotary chain tensioning sprocket to apply constant tension in the chain, a measuring device for repeatedly measuring the movement of the chain tensioning sprocket as the chain moves along its length and when constant tension is applied to the chain by the chain tensioning sprocket, detection means for comparing the measurements of the movements of the rotary chain tensioning device and for estimating the remaining operational life of the chain based on the distance of linear movement of the chain tensioning device at different times.

2. The chain measuring device of claim 1, wherein the tunnel oven is a baker's industrial oven, and the continuous link chain comprises a roller chain.

3. The chain measuring apparatus of claim 1, wherein: said chain tensioning device comprises a chain tensioning sprocket engaged by the continuous chain as the continuous chain moves along its length, and force application means for applying force against said chain tensioning sprocket to create a predetermined tension on the continuous chain as the continuous chain moves along its length.

4. The chain measuring device of claim 1, wherein: the path comprises a baker's industrial oven, the conveyor link chain comprises a roller chain, the chain tensioning device comprises a chain tensioning sprocket that engages and rotates in unison with the movement of the chain.

5. The chain measuring device of claim 1, wherein said detection means is selected from a group consisting of: an optical scanner, a resistance transducer and wire, ultrasonic distance sensor, or linear position sensor.

6. A chain measuring apparatus for measuring the wear over time of a continuous chain extending through a heated oven and moved without interrupting the movement of the chain, comprising: a chain tensioning sprocket in engagement with said chain for guiding the continuous chain along a continuous path through the oven and through a U-shaped path, a fluid actuated piston positioned to urge the chain tensioning sprocket at a predetermined constant force toward the U-shaped path of the chain, sprocket moving means configured for urging said chain tensioning sprocket in an intersecting direction toward the continuous path of the continuous chain to guide the continuous chain in a U-shaped path about said chain tensioning sprocket and to apply tension in the whole continuous chain, and detection means positioned to detect the position of the chain tensioning sprocket.

7. The chain measuring apparatus of claim 6, wherein said sprocket moving means comprises a fluid actuated piston positioned to urge the chain tensioning sprocket at a predetermined constant force toward the U-shaped path of the chain.

8. The chain measuring apparatus of claim 6, wherein said sprocket moving means is moveable with a predetermined force into a U-shaped path of a roller chain to apply continuous tensioning force to the chain, such that the length of the chain is measured by detecting the movement of the chain tensioning sprocket into the U-shaped path of the chain and measurement of movement of the chain tensioning sprocket indicates a change in the length of the whole chain, which, in turn, indicates the wear on the parts of the chain and the expected operative life of the chain.

9. A chain measuring apparatus for measuring the expansion of a chain including a continuous chain including a U-shaped span, a chain tensioning device positioned in the U-shaped span of the continuous chain for applying a predetermined force to the chain toward the U-shaped span, and measuring means positioned for measuring the movement of the chain tensioning device into the U-shaped path of the chain.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1A is a side elevational view of a segment of an oven roller chain.

[0037] FIG. 1B is a top view of the segment of the roller chain of FIG. 1A, showing a connector pin and a bearing sleeve in the left two links, and the assembled rollers in the right two links.

[0038] FIG. 2A is a side elevational view of a segment of another type of oven roller chain.

[0039] FIG. 2B is a top view of the segment of a roller chain of FIG. 2A.

[0040] FIG. 3A is a side view of a chain tensioning sprocket, a driving sprocket, and a portion of the oven roller chain extending in a U-shape about the chain tensioning sprocket, with the cylinder and its piston that apply the force to the chain tensioning sprocket.

[0041] FIG. 3B is a top view of the chain tensioning socket and the cylinders that apply linear force to the chain tensioning socket.

[0042] FIG. 4 is a perspective view of the hydraulic unit that includes the air over liquid pump and the hydraulic fluid tank for charging the hydraulic cylinders of FIGS. 3A and 3B.

[0043] FIG. 5 schematic view of the control circuit that controls the force applied to the chain tensioning sprocket.

DETAILED DESCRIPTION

[0044] Referring in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIGS. 1A and 1B illustrate a segment of an endless roller chain 9 of the type that may be used in a tunnel of a baker's oven. FIGS. 2A and 2B illustrate a segment of another endless roller chain 119 also of the type that may be used in the same environment. Other types of chains may be used. As shown in FIG. 3A, the roller chain, such as chain 9, extends about a driving sprocket 8 and about a tensioning sprocket 23 and about other sprockets (not shown) that support and guide the chain.

[0045] As shown in FIGS. 1A and 1B an embodiment of a roller chain 9 has links 10 and each link may include a pair of parallel side plates 12, 13 that have end portions that overlap the side plates of the next adjacent chain links, and connector pins 14 that are mounted through the overlapping ends of the pairs of side plates. Rollers 18 are mounted on the connector pins 14 between the parallel side plates 12 and 13. Spaces 20 are located between and on opposite sides of each roller 18, between the side plates 12 and 13.

[0046] The teeth 24 of the sprockets 8 and 23 (FIG. 3) fit into the spaces 20 on opposite sides of the rollers 18 and their connector pins 14 for advancing and guiding the roller chain through the passage of a tunnel oven, as is conventional in the art.

[0047] The side plates 13 on one side of the roller chain 9 each may include a mounting flange 15 (FIG. 2) that extends at a right angle from the side plate, horizontally to one side of the direction of travel of the roller chain, and baking pans 26 (FIG. 3A) may be mounted to the mounting flanges 15 for carrying the work products along the chain and through the oven.

[0048] FIGS. 2A and 2B illustrate another type of roller chain that may be used for baking ovens. As with the chains illustrated in FIGS. 1A and 1B, the chain links 110 of the roller chain 119 of FIGS. 2A and 2B each include a pair of parallel side plates 112, 113 that have end portions that overlap the side plates of the next adjacent chain links, and connector pins 114 that are mounted through the overlapping ends of the pairs of side plates. Rollers 118 are mounted on the connector pins 114 between the parallel side plates 112 and 113. Spaces 120 are located between and on opposite sides of each roller 118, between the side plates 112 and 113. A pan connector 115 is mounted to the links 112 and 113.

[0049] Other types of continuous chains and baking pans may be used with this invention.

[0050] FIG. 3A illustrates the chain tensioning device 22 that includes chain tensioning sprocket 23 of a conventional roller chain, with the roller chain 9 or 119 extending through the chain passage of a baker's tunnel oven (not shown). Both sprockets have a plurality of circumferentially spaced teeth 24 that extend radially outwardly from the perimeter of the sprocket and are sized and shaped and positioned to fit into the spaces 20 or 120 of the chain links 10 and 110, on opposite sides of rollers 18, 118. The drive sprocket 8 that may be similar in design to the chain tensioning sprocket 22 moves the continuous chain through the oven and about the chain tensioning sprocket 23 as indicated by the direction arrows 25 and 31 of FIG. 3A.

[0051] As shown in FIG. 3B, the chain tensioning device 22 may include a pair of fluid activated cylinders 28, each with a piston 29 extending on opposite sides of the chain tensioning sprocket 23. In response to the pressure applied by the cylinders 28 to pistons 29, the pistons 29 urge the chain tensioning sprocket 23 toward the inside of a U-shaped path 31 formed by the roller chain about the tensioning sprocket 23 as the roller chain passes about the tensioning sprocket. This applies linear force 27 to the chain tensioning sprocket that, in turn, pushes the chain tensioning sprocket 23 toward the inside of the U-shaped path 31 of the roller chain and tends to apply tension to the entire length of the roller chain, including the span of the continuous chain that extends entirely through the oven (not shown). The chain tensioning sprocket 23 is free to rotate about its own axis 30 in response to the movement of the roller chain by other driven sprockets 8. The linear movement 27 of the chain tensioning sprocket into the U-shape of the roller chain indicates the expansion of the entire length of the roller chain, and measurement of the linear movement of the chain tensioning sprocket and comparison of the linear movement with linear movements previously taken indicates the amount of expansion of the chain between measurements.

[0052] The control system for the fluid actuated cylinders 28 should be capable of applying a constant fluid pressure to the cylinders to apply a constant predetermined force to the chain tensioning sprocket 23. Various fluid circuits may be used.

[0053] For example, FIG. 4 shows the control system for the fluid actuated cylinders 28.

[0054] The control system 30 includes tank 32 for supplying hydraulic fluid that is to be provided under pressure to the cylinders 28 of FIGS. 3A and 3B, cage 33, manual pump 34, check valve 35, needle valve 36, plug 37, and needle valve 38. The two-way direct acting solenoid valve 39 is mounted adjacent the needle valve structure 38. Two-way solenoid valve 40 is mounted to the attachment box that is, in turn, mounted to the tank 32. Haskel pump 42, that is a gas over liquid pump, is mounted atop the tank 32 and communicates with the conduit extending from the valve 43.

[0055] As shown in FIG. 5, the electrical/hydraulic circuit communicates with the cylinders/pistons 28 and 29 of the chain tensioning sprocket 23 (FIG. 3). The hydraulic system includes a pneumatic filter A, a poppet valve B, and an effector C. The filter A is a combination of filter, regulator, and shut-off valve. Effector C is a pressure transducer, and two-way poppet valve B supplies air pressure when the pump is to be activated and air pressure is applied to the Haskel pump 42. When the system is to be shut down, the system will go back to zero mechanical energy and the valve B will just vent to the atmosphere so that there is no air pressure on the system.

[0056] The Haskel pump 42 communicates with a needle valve 52. When the needle valve 52 opens, the oil will flow down to either position 3, position 4, position 5, or position 7. When pumping up the hydraulic oil, at position 51, the pump has a line that goes down the tank and sucks oil from the tank.

[0057] There is a line coming from the pump down to the tank. Another line from the tank extends into the manual pump 10. With regard to the pneumatic pump, there is a call for pressure. On the air side B there is an air valve that will let air flow through to the pump. The pump is a positive displacement device so as the pump sucks up oil and pushes it along, it now has a vacuum so more air will go in and move the cylinders to bring up more oil. Oil will travel out at P1 of the valve body. The oil moves inside the big aluminum valve. The oil moves through a needle valve 2 and the pressure of the oil may be measured by gauges 114, 115 and 111. That prevents high pressure jolts of oil from moving that valve too much and moving the cylinder too much to avoid breaking the pressure gauge by exposing it with hard blasts of pressure.

[0058] The arrangement dampens the pressure so that high spikes of oil pressure are avoided. This prevents the gauge from being damaged. Ball valve 119 charges the pressure gauge. When the ball valve is closed, the snubber is removed and the pressure gauge can be relieved if the chain is to be serviced. The oil travels down to another needle valve 2, then goes down to needle valve 4 which is a two-way solenoid. At that point the oil moves out to 5 or the oil is returned to the tank. The oil flow is controlled so that it can go in either direction.

[0059] A bleeder valve may be opened to bypass oil back to the tank. A two-way manually operated valve may be positioned in the down position if there is a failure in the pump. If there is a failure of the pump, the operator may move a valve to activate the manual pump.

[0060] The pressure that's going out to the cylinders is measured and may be adjusted. With this arrangement the pressure of the gas may be changed.

[0061] For example, if the oven is cold and if the desired hydraulic pressure to be communicated to the cylinders 28 is 1000 psi, the pressure in the cylinders is increased until the pressure in the cylinders is 1000 psi and the system is ready to be heated for baking operations with the oven running. But as the oven heats up, the roller chain will expand due to its thermal expansion. The roller chain will reduce the pressure against the two cylinders because the chain is getting longer due to thermal expansion. But the pressure transducer measures the pressure and it sends a signal back to the PLC that says run the pump. The pump gets the hydraulic pressure back to 1000 pounds and stops again. This may happen fifteen times in the first hour. It may happen ten times in the second hour and five times in the third hour, depending on conditions such as changing temperature of the roller chain, oven and tensioning sprocket 23, etc.

[0062] Once the oven is fully expanded due to the application of heat, the number of corrections of force applied by the chain tensioning sprocket is reduced. It usually takes 2 or 3 hours to stabilize the temperature of the roller chain. Once the temperature of the roller chain is substantially stabilized, there might be another correction signal for changing the force of the cylinders through the course of the day. An object of the process is to maintain a constant pressure against hydraulic cylinders so that the tension applied to the oven chain is constant. That results in tension being applied against the chain at all times during the operation of the oven.

[0063] Another advantage of the system is when the system disclosed herein is to be shut down at the end of the day, solenoid valves are opened and bleed the oil back to the tank and reduce the pressure in the hydraulic cylinders down toward zero. This relieves the forces on the chain tensioning sprocket 23 and on the continuous roller chain 9, so that the chain can be more easily inspected and lubricated, etc. Also, as the chain usually is allowed to cool overnight when the oven is not in operation, and the chain does not have to cool under tension.

[0064] While the chain management system described above has been described in connection of a baker's tunnel oven, it may be used in connection with intermediate proofers, final proofers, racetrack coolers, spiral coolers, in-ground basket transport systems and possibly in many other types of chain applications. The disclosed chain management system allows plant engineers to predict when the chain needs to be replaced instead of waiting for failure. The system also allows the engineers to predict when the chain should be lubricated.

[0065] The chain management system may monitor the expansion of the chain from the first operation of the oven. It can be programmed to measure the roller chain of a baker's oven chain every time the oven is started hot or cold and maintain the measurement in the memory of a PLC. At the end of any period, such as the end of a calendar quarter, there can be an output available from previous chain measurements to inform the plant engineers of how much expansion of the chain has occurred between measurements and how much the chain has worn during that period. And, based on the differences of the measured lengths of expansion of the entire length of the chain, an accurate estimate of remaining chain life may be obtained by comparison with previously established histories of the performances of other similar roller chains.

[0066] The chain management systems may use various measuring devices to measure the length of a chain, such as by attaching a laser, IR beam, resistance wire, or ultrasonic measuring device to a fixed position near the chain tensioning sprocket on the frame of the oven. The chain measuring device is focused on the movable chain tensioning sprocket. Each time the oven starts, the position of the chain tensioning sprocket may be recorded and compared to its previous position. This distance may be measured in time increments such as every 5, 30, 60, 300, or 750 seconds and the measurements may be stored in the memory of a PLC. The PLC translates this measurement into inches or millimeters along with the temperature of the chain and displays an output on an operator interface. The PLC can track this measurement until the oven is turned off, and it may continue to track it until the oven has cooled. The operator interface output is in the form of a graph (line, bar, column) and shows the changes in the length of the chain due to temperature and wear. The plant engineer can decide to let the data remain in the PLC or download it into the plant SCADA system.

[0067] The chain management system also incorporates a device, such as an inverter, transducer and other metering devices to measure the work of the chain. The PLC will track the work and output of the work in the form of a graph such as a line, bar, or column graph. By tracking the work precise data can be maintained on the load of different products and pans in the oven. In the event of an indication of a high change in work load, the PLC may be programmed to signal an alarm and prevent a catastrophic oven breakdown. Further, in a tray oven the trays may be marked with sequence numbers and the number of the tray that is at the front of the oven will be recorded at the alarm.

[0068] The chain management system can be supplied with all new oven tray, grid, plate, mesh belt, intermediate tray proofers, final proofers including rack, tray, and conveyorized stabilized tray, and coolers such as rack, spiral, race track, and continuous coolers, and in-ground basket transport systems. The chain management system also can be retrofitted into existing machines mentioned above.

[0069] The chain management system not only can be used for ovens, but may be used for other devices such as, but not limited to, intermediate proofers, final proofers, racetrack coolers, spiral coolers, and in-ground basket transport systems. The chain management system will allow the engineers to predict when the chain needs to be replaced instead of after failure. It will also allow the engineers to predict when the chain should be lubricated.

[0070] While this disclosure describes a system of measuring the change of length of a continuous roller chain, the system may be applied to other continuous items that have tension applied thereto, including other types of continuous link chains.

[0071] Although a preferred embodiment of the invention has been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiment can be made without departing from the spirit and scope of the invention as set forth in the following claims.