Title of Invention

THE PRODUCTION SYSTEM FOR ASSEMBLING MILLING MACHINES

Abstract

This invention relates to a novel production system for use in a manufacturing industry, which employs an arrangement of the various processes involved, into pre-defmed cells. Each of these cells have a certain number of tasks performed within them, these tasks being decided upon to maximize throughput, minimize movement of parts around the assembly line, reduce number of operators involved, minimize space requirements. and ensure a smooth flow of materials through the assembly line. The parts or materials that are to be used in each of these cells are prepared as kits and ordered as sets. There are also provisions for buffer zones to aid in the preparation of kits for use in the cells, packing areas for the machine to be fmally dispatched and stock areas that enable storage of machines awaiting customer inspection, past a designated time-period.

Full Text

FIELD OF THE INVENTION This invention relates to a novel production system for use in a manufacturing industry. BACKGROUND Existing Production Methodology: Normally, the assembly of a product or machine is done in one place and the parts required are kept nearby. An example of such system is shown in Fig. 1. The machines are assembled in the front (area A) and the parts are kept at the backside of the machines (area B). A minimum of 4 assembly technicians are required to assemble a machine 1) one for structure assembly 2) one for fixing the gearbox 3) one for electrical wiring and routing 4) one for inspection. Once the machine is ready, the customer is called for inspection. After the customer clearance, the machine is shifted to the packing area and the machine is dispatched. The disadvantages of this system are : 1) a minimimi of 4 technicians attend to the machine in the same place. This leads to the waiting of one person till the other person completes his activities - hence increasing the throughput time. 2) The parts are kept in an acciraixilated way causing a chaotic flow of materials during assembly - hence time delay and fatigue to the assembly technicians. 3) Difficulty in the assessment of progress of the assembly work, 4) Difficulty in the assessment of the shortage of parts supply. 5) Lesser production rate 6) More throughput time required for assembly 7) Time delay in searching for new place to assemble next machine if the previous machine is waiting for the customer inspection. This system is widely practiced but is not suitable for the present day reqxiirements where the customer requires the machine in a very short time. There is a need to find a way to reduce the throughput time and at the same time increase the volume of production. This new system proposed by the present invention is called as Akshara Production System (APS), which is a plaiming and execution methodology for realizing high volumes of a machine. This production system is developed to produce various versions and models of the product or the machine in small assembly space, deploying least manpower and in the least production throughput time. DISCUSSION OF PRIOR ART Various assembly lines are known in the automobile industry. U.S. Patent No. 6,948,236 discloses an assembly line used to assemble side panels for automobiles. Conventional side panel assembly lines for automobiles are also foxmd in Japanese laid-open patent No. 62-263876. U.S. Patent No. 6,918,168 discloses a method and apparatus to assemble a vehicle's body. U.S. Patent 6,516,935 discloses a more generic industrial assembly line using conveyors to conmiunicate parts between the different stages of production. The existing systems are widely practiced but are not suitable for the present day requirements where the customer requires the machine in a very short time. SUMMARY OF THE INVENTION It is an object the present invention to provide a novel production system based on first dividing the assembly into cells and then grouping of the required parts for each cell as bits. In the new Akshara Production System, the material lists are prepared as kits. Based on the number of parts and the activities involved, the assembly is divided into 4 cells. The parts required for each cell are grouped as kits (totally 4 kits). These parts are ordered as sets. After the receipt of the parts they are issued to assembly and kept in the designated area in each cell. Cell 1: In this cell, the structural assembly is carried out. The pre-assembled milling head, structural elements like base column, table, cross side and the axis guide ways and ball screws are the major items for this cell. Cell 2: In this cell, the electrical cabinet, pendant and machine guards are added to the structural assembly. The lubrication and coolant connections are made. The machine is energized (power connection is made and checks are in place for the fimctional aspects of the machine). Cell 3: In this cell, the system and servo control tuning, running tests, accuracy tests, cutting tests etc. are conducted. In addition to this, the machine-moxmted options like centralized automatic lubrication system, automatic tool clamping system, table guards, coolant gun etc are fitted onto the machine as per the customer requirements. Cell 4: In this cell, the machine kept ready for customer inspection. In addition to this, the optional accessories (which do not require any fitment on to the machine like air compressor, tool holders, voltage stabilizer etc) and the instruction manuals are kept ready. After inspection of the machine by the customer and his clearance, the machine is shifted to packing area for dispatch. Machine stock: If the machine is waiting for the customer's inspection, it will affect the flow of the assembly. In that case, the completed machines are shifted to the STOCK AREA so that assembly of next machines is not affected. Assembly kits: The materials for each cell will be kept in the place identified in each cell. It is plaimed to assemble 4 machines at a time in each cell. The assembly will start after ensuring that all the required materials are kept in the places identified. By looking at the marked area itself, one can judge whether all the items are available or not. Once the kit is complete, the assembly will start. When the previous four assemblies are getting on, two more kits will be made ready in these buffer areas. The assembly activities are clearly defined in each cell. These activities are balanced in such a way that it will take two complete days for assembly of one machine in each cell. This means one machine will be completed in all respects in 6 days. (2 days each in cell 1,2 and 3). The machine will be transferred to Cell 4 at the end of 6^ day. Each cell area is clearly identified and marked to assemble 4 machines at a time with 4 assembly technicians. In this way, with 16 technicians, 4 machines will be coming out of the production line in every 2 days on a continuous basis. This accounts for 12 machines in a 6 day work week and will give a production of 52*12=624 machines in a year. With 80% overall efficiency of the system, 624 * 0.8 = 500 machines can be realized in this method with 16 assembly technicians. In this production system, it is easier to accommodate the fluctuations in demand. In case the product is moving fast in the market, the dispatch area will have less or no machines. On the other hand, the number of machines in the dispatch area will be increasing, waiting for customer. In both the cases, the production-in-charge can quickly take decisions by looking at the cells and alter the production program accordingly. Advantages of the system The advantages of the new system are: 1. Reduced throughput time. 2. Clearly defined assembly sequence - hence no time delay. 3. Ease of monitoring the assembly progress. 4. Ease of monitoring the supply shortage. 5. Higher production. 6. Lesser space requirement but higher volimie of machines produced. 7. Monitoring the production according the material flow and order in-flow fluctuations. 8. Next machine's assembly is not disturbed when the previous machine is waiting for customer. BRIEF DESCRIPTION OF DRAWINGS Fig 1. illustrates the full assembly divided into 4 cells of the production system of the present invention; Fig. 2. illustrates cell 1 of the production system; Fig. 3. illustrates cell 2 of the production system; Fig. 4. illustrates cell 3 of the production system; Fig. 5. illustrates cell 4 of the production system. Fig. 6. illustrates the Akshara Machine/production center, produced by going through the Akshara assembly process. DETAILED DESCRIPTION OF THE INVENTION It is an object of this invention to reduce the throughput time, simultaneously increasing the volume of production. In the existing systems, shown in Fig. 1, the machines are assembled in the front (area A) and the parts are kept at the backside of the machines (area B). Minimum of 4 assembly technicians are required to assemble a machine i.e. first one for structure assembly; second one for fixing the gearbox; third one for electrical wiring and routing; and fourth one for inspection. Once the machine is ready then the customer is called for inspection. After the customer clearance, the machine is shifted to the packing area and the machine is dispatched. In the Akshara Production System of the present invention, the assembly sequence is demarcated into pre-defined parts, each being performed in it's own cell. Herein, we describe the assembling of Akshara Machine/production center as an example , that is produced as a result of going through the Akshara Production System. This is a novel production system that provides a planning and execution framework and methodology, for realizing high-volume production, maximizing the diversity of produced machines, minimizing the necessary assembly space, minimizing manpower deployed and maximizing throughput comprising: EXAMPLE 1, production of Akshara machines, as illustrated in Figs. 6, 7 and 8. Cell-1 In this stage, the base column is placed on the leveling pads and the base leveled. Paint and grease from the machined surfaces are removed. LM guide-ways for the Y & Z axes are mounted on the base column and the C axis on the cross slide, shown in Fig. 6, part 1. The ball screws are mounted on the base column 2 and the cross slide, and the bearings pre-loaded. The table 3 is then mounted on the cross slide and the whole assembly is moxmted on the base-column 2. In the next step, pre assembled spindle gear box assembly 4 is moimted on the column 5. Chain, sprocket and the counter balance weight is assembled. The axes motors, namely, X, Y & Z axes, shown in Fig. 7, are mounted and the drive to the ball screws provided through belt and pulleys. Once all these assembUes are over, the geometry of the machine is checked as per the BFW standards and corrections, if any, are done. Now the machine is ready to move to Cell-2. The Milling head cover 7 covers the milling head 14, manual drawbar 15. The electrical cabinet 8 includes the main switch 10 and control panel 16. A bellow cover 17 is also provided for the milling head 14. X-axis hand crank 18 and Y-axis hand crank 19 are provided on the table 3. The chip tray 20 is mounted on the base column and placed below the table 3. The speed selection chart 21 and gear shift levers 22 are placed on the side of the milling head 14. Foundation bolt 23 is provided for fixing the base column 2. CeU-2 The machine is placed in Cell-2 and the leveling of the machine done. The lubrication tank, piping to the different locations where lubrication is required, fitting of metering cartridges are done initially. After this is complete, the coolant system fitment and assembly is done. This includes fitting of the coolant pump in the tank, piping to the cutting area and the fitment of coolant nozzle. The pneumatic connection, fitment of the FRL imit, piping and assembly of the de-clamp cylinder are completed. The telescopic covers, shown in Fig. 6, part 6, for protection of the ball screws and guide ways are fitted for all the three axes. Also the table guards and milling head cover, shown in Fig. 6, part 7, are fitted. The next set of operations is the fitment of the electrical cabinet, shown in Fig. 6, part 8, on the column. The wiring fi-om the cabinet to the different elements like motors, shown in Fig. 6, part 9, switches 10 etc. are done. After these connections the machine is energized and all the axes movements checked. Cell-3 The machine is moved to Cell 3. In this cell the basic testing of the machine is done. The spindle stabilization test is the first one where the spindle, shown in Fig. 6, part 10, is run as per the BFW standard test process. This takes about 6 hours. The spindle temperature, noise etc are checked. Then the axes testing program is run where all the three axes, shown in Fig. 6, part 11, 12 and 13 are run in a program to test the performance. Geometry of the machine is completely checked as per the BFW test chart. After this load test is carried out where a test piece of specified matmal properties is cut on the machine for the maximum material volume removal, which is 80 cc per minute. Laser calibration of the axes are carried out in the ext step. This test checks the positioning accuracy and the repeatability of positioning using the laser testing equipment. Ball bar test for circular accuracy, drilling, tapping testing is also done on some of the machines as per our audit frequency defined. CelM This is the final cell in this manufacturing set up. The pre-tested machines are moved to this cell. In this cell the demonstration and testing of the machine for the customers is carried out. The tests include geometry test for all the axes, coolant test, fimctional test, load test for material removal capability and any other specific tests, if demanded by the customers, is carried out. Training on the basic operations of the machines is also carried out for customers, if required. After these trials are over, the fmal coat of paint is applied, name plates, are fixed and all the axes locked for shipment of the machine. A final inspection is done to verify supply scope and the machine is made ready for dispatch. We Claim: 1. A novel production system that provides a planning and execution framework and methodology, comprising: four cells, with the parts used in the activities within each cell grouped into kits, these parts being ordered as sets and placed in a designated area within each cell; the cells having marked kit areas, with a certain number of these being buffer zones for the preparation of kits contemporarily with the production activities within the cell; the assembly activities being clearly defined in each cell, and being balanced in a manner that sets time limits for the completion of each cell's activity; the production system having these cells, thereby being able to accommodate fluctuations in demand, also providing the production-in-charge a clean overview of materials that are either required or are holding-up the flow through the pipeline, enabling them to make quick decisions to avert any delays. 2. The production system of claim 1, wherein the processes involved in structural assembly are carried out in Cell 1. 3. The production system for assembling milling machines, wherein candidate parts for Cell 1 preferably include pre-assembled milling heads, structural elements like base columns, tables, cross slides, axis guideways and ball screws. 4. The production system of claim 3, wherein processes such as the addition of electrical cabinets, pendants and machine guards to the structural assembly, the lubrication and addition of coolant connections, energizing the machine, making power connections and other wiring and checking functional aspects are carried out in Cell 2. 5. The production system of claim 4, wherein processes such as system and servo control tuning, testing (for accuracy, cutting etc.) and addition of machine- mounted options such as the centralized automatic lubrication system or optionally, the automatic tool clamping system, table guards, coolant-guns etc. are carried out in Cell 3. 6. The production system of claim 5, wherein the machine is kept for customer inspection, with optional accessories that do not require to be fitted on the machine, such as air-compressors, tool holders, voltage stabilizers, instruction manuals etc. being placed in Cell 4. 7. The production system of claim 6, wherein the machine is shifted to a packing area for dispatch after the customer has completed inspection in Cell 4. 8. The production system of claim 7, wherein the machine is moved to a pre- designated stock area, in case the machine is awaiting customer inspection over a certain amount of time, primarily to ensure a smooth flow through the assembly line.

Documents:

1297-che-2004 abstract-duplicate.pdf

1297-che-2004 description (provisional)-duplicate.pdf

1297-che-2004 drawings-duplicate.pdf

1297-che-2004 form 2.pdf

1297-che-2004 power of attorney.pdf

1297-che-2004-abstract.pdf

1297-che-2004-claims.pdf

1297-che-2004-correspondnece-others.pdf

1297-che-2004-correspondnece-po.pdf

1297-che-2004-description(complete).pdf

1297-che-2004-description(provisional).pdf

1297-che-2004-drawings.pdf

1297-che-2004-form 1.pdf

1297-che-2004-form 18.pdf

1297-che-2004-form 5.pdf