FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"A SEQUENTIAL AND SYNCHRONOUS TIGHTENING SYSTEM DURING
ASSEMBLY OPERATIONS"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C, SATPUR,
NASHIK - 422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF THE INVENTION:
The present invention is related to manufacturing systems and methods. More particularly the present invention is related to assembly line of an automobile vehicle wherein the assembly of the engine and gearbox is executed.
BACKGROUND OF THE PRESENT INVENTION:
Conventionally, the sequential and synchronous tightening in the industry is done by using the human labour. This method requires the skilled workers suited for the job. It focusses upon building critical skills amongst employees through reargues training and coaching to perform critical assembly function. Such training includes - basic skill building through dexterity, skill evaluation through assessment, on the job training for skill enhancement, writing and following SOPs (Standard Operating Procedures), putting additional inspection points etc.
The drawback of this conventional method is that the activity is highly operator dependent and therefore the chances of human error are involved in the activity. There are chances that there is unwillingness of operator to work on stage. NVA (non-value added activities) and additional manpower for inspection is required which directly effect on the output and quality as well.
In some industries, some sophisticated methods are used for sequential and synchronous tightening that involves an automated man less work station. Though automated workstations are becoming increasingly popular to improve performance and productivity, it is quite costly. Automated multipurpose work stations are also deployed if required. It focusses upon deployment of a full proof assembly process eliminating operator dependency, high skill requirement & human error involved so far.
The drawbacks of this method are that it is a customized system and therefore is rigid in adopting unforeseen changes. It involves high initial cost and huge space requirement. It requires higher cost of modification and are very critical for maintenance purpose.

OBJECTIVES OF THE PRESENT INVENTION:
The main objective of the present invention is to provide a sequential and synchronous tightening system on the assembly line.
Another objective of the present invention is to provide a sequential and synchronous tightening system on the assembly line wherein the said system is maintenance free, easy to operate and does not required the skilled man-power.
Another objective of the present invention is to eliminate the requirement of skilled and costly man-power required in sequential and synchronous tightening system.
Still further objective of the present invention is to improve the productivity and quality on the assembly line by providing sequential and synchronous tightening system.
STATEMENT OF INVENTION:
Accordingly invention provides a sequential and synchronous tightening system, during assembly operations, comprises a CPU configured to receive, code and process the data as per the given set of parameters, of input module having a bar code scanner to scan barcode on the engine, linear encoder and push button; an output module connected to the said CPU having an electrical tool with controlling function to function such that to receives data from CPU & triggers electrical tool for the operation (i.e. for bolt tightening) and accordingly provides feedback to CPU for Torque OK / Not OK.; a conditional indicators provide to said output module to function such away that to indicate various operating conditions to the operators - e.g. Tool position, Torque OK, Torque Not OK, Cycle OK etc. and a conditional indicators.
DESCRIPTION OF THE FIGURES:
The objectives and advantages of the present invention will be understood reading following specifications in conjunction with the figures, wherein
Figure 1 shows block diagram of the system for sequential and synchronous tightening in accordance with the present invention.

Figure 2 shows block diagram of the central processing unit of the present invention. Figure 3 shows the working flowchart of the system explaining the method of sequential and synchronous tightening system. Figure 4 shows different types layouts of engine and gear box combinations.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:
In modern automotive manufacturing, use of electric tools for assembly operations is increasing day by day. For critical assembly operations requiring highest Quality, Productivity & Delivery, use of multi spindle electric tools is common. But for some critical assembly operations, no ready solution is available, where use of multi spindle tools is advised & still not possible due to product profiles or other product design constrains. Now this leads to a situation, where product features cannot be altered for manufacturing requirements. To tackle this situation no solution is available which is low cost, simple, fast yet equally effective.
The above described situation triggers birth to the problems like (i) Multi spindle tool can't be used due to product design & features; (ii) Low cost solution for synchronous & simultaneous tightening operations; (iii) Operator skill dependency for synchronous & simultaneous tightening; (iv) Generation of defects & rework; and (v) High chances of processing defective products & poor reliability to end user / customer.
To address all these problems the present invention is proposed wherein the system allows assembly operation by two operators only in synchronous mode, thus two human beings work in tandem as a single mechanical unit.
Referring to figure 1 the system comprises of input module, central processing unit and output module. The input module further comprises of bar code scanner, linear encoder and push button. The bar code scanner is used to scan printed barcode on engine and accordingly sends data to CPU (Processing unit). Linear encoder provides feedback for tool position with respect to a preset zero position and sends data to CPU. The push button provides feedback for start of tool operation and sends data to CPU.
Referring to Fig. 1, the system comprises of barcode scanner (1), Central processing unit (2), torque tube assembly (3) two in number, portable electric tools (4) with press button, linear encoder (5) and display panel (6).

The bar code scanner (1) scans 2D barcode from engine assembly. It trigger the Start of the process through scanning of model code barcode on the engine assembly. It communicates with CPU and sends data for engine model code that helps the CPU to identify type of engine.
Central processing unit (2) receives data from barcode scanner, decodes it and process the data as per the given set of parameters. It functions as the heart of the system. It works on a predefined matrix that consists of - Engine type, predefined sequence of operation & torque value for the same. It receives data from barcode scanner, analyzes it and then identifies the type of engine (model no) and thereby the sequence with position of tightening & torque to be applied as the sequence as the Torque requirement differs from model to model. It further receives data from liner encoder & compares with pre-set information of tool position with respect to model code. It also receives data from electric tool operation (for cycle start & torque OK conditions) through push buttons, compares with the required position (point 1 & 2 as shown in figure 1) for synchronous operation and then accordingly sends correct data to output module. It is also responsible for display of information on display panel like Torque OK - LH /RH & cycle completion.
Torque tube assembly (3) are two in numbers. It holds electrical tools & linear encoder. It holds electrical tools with cables on LH & RH side. Provides smooth vertical & angular movement to the tools. Also, it houses the LINEAR ENCODER assembly on top, which is connected with electrical tools. It is mounted on a predefined fixed height from ground, it provides an imaginary ZERO LINE necessary for system function. It is a mechanical assembly unit that acts as an interface between CPU, LINEAR ENCODER & Electric tool.
Portable electric tools (4) with push buttons are used (on LH and RH) to fasten the bolt and deliver correct, required torque. It receives data for torque from CPU. Gives feedback for start of tightening operation & delivery of correct torque to the CPU.
Linear encoder (5) gives feedback for tool position with respect to a predefined Zero line and sends data to the CPU. It interlinks age with CPU through continuous feedback of tool position with respect to a predefined zero position.
Display panel (6) displays OK positions for torque delivery & cycle completion. It provides visual indication to stage operators, for Torque delivery & cycle completion. It receives data from CPU for Torque delivery & cycle completion & displays the same to stage operators.

The CPU of the present invention is configured to receive, code it and process the data as per the given set of parameters. It receives data from barcode scanner, analyzes it and then identifies the type of engine (model no) and thereby the sequence with position of tightening & torque to be applied as the sequence and torque requirement differs from model to model. It further receives data from liner encoder & compares with pre-set information of tool position with respect to model code. It also received data from push buttons, compares with the required position (point 1 & 2 as shown in figure 1) for synchronous operation and then accordingly sends correct data to output module.
The output module comprises of controlling function of electrical tool and conditional indicators. The controlling function of electrical tool receives data from CPU & triggers electrical tool for the operation (i.e. for bolt tightening) and accordingly provides feedback to CPU for Torque OK / Not OK. The conditional indicators indicate various operating conditions to the operators - e.g. Tool position, Torque OK, Torque Not OK, Cycle OK etc.
The system uses two portable electric tools for operation. Soft data like- various models, sequence of operation & torque values at various positions are programmed in the controllers for electric tools. The system uses liner encoder for operation. Both tools stand inoperative at any point in time. To start the cycle, operator needs to scan the model code on engine. It sets the model code, sequence to be followed & torque for tightening. Further if one operator finishes early, he cannot leave his tool/position till the second operator completes his work, otherwise system generates an error & stops working. Thus both operators work as a single working unit.
The invention here in the system is making two portable tools work as a single unit by ensuring it to work only at required position in simultaneous and synchronous tightening mode. This forces two operators to work in tandem as-a single unit.
This it gives a cost effective solution with huge scope of horizontal deployment across the industry. The system is applicable in part assemblies for simultaneous and synchronous tightening in following areas.
- Body shell mounting bolt tightening on chassis assembly.
- Wheel mounting nut tightening.

- Rear suspension (Multilink) assembly tightening.
Referring to Fig. 3, the sequential and synchronous tightening system operates in following steps.
1. Initial Condition - Both Lh & Rh side electrical tools stand inoperative.
2. To start the cycle, operator needs to scan the barcode provided on engine (Component 1 in Fig.1).
3. This barcode defines the engine type.
4. This data is sent to CPU. (Data A in fig. 1)
5. CPU recognizes the engine type & sets the torque value with required tightening sequence for the engine.
6. To proceed further, operator needs to move the tools to the required bolt tightening location on engine.
7. Tool movement / position is read with respect to a predefined zero line position by the encoders mounted on torque tubes.
8. This data (analogue reading) is continuously sent to CPU. (Data B in fig.1)
9. When correct, required position is achieved by the tool, it is displayed to the operator on CPU. (Operator to repeat step 6 to 8 as/if required)
10. With this CPU enables both tools (Data C in fig.1) so that they can be used for bolt tightening.
11. To operate the tool, both operators need to press the switch simultaneously.
12. Tools operate only when both LH & RH side tool are at correct required position, both operators pressing the operating switch on tool. Further, tools remain operative till both the operators keep on pressing the switch at correct required position.
13. Thus system operates only when both operators work simultaneously & synchronously.
14. Torque OK feedback is provided by the tool to CPU. (Data D in fig.1)
15. When feedback for both Lh & Rh side tool is received by the CPU, Torque OK is displayed on display panel. (Data E in fig.1)
16. To complete the next scheduled sequence of tightening, operators need to repeat the sequence from point 5 to point 12.
17. When total sequence is completed, 'CYCLE OK' is displayed on display panel. (Data Fin fig.1)
18. This allows the engine to move to next stage.
19. It also resets the system to initial condition waiting for next engine.

The unique features of the present invention are as under:
- It's a universal design and therefore this concept can be easily adopted / installed to any type of assembly operation using two or more electric portable tools.
- Use of linear encoder. In this invention a linear encoder is used to measure tool movement in vertical axis with respect to a preset zero position. This allows to identify tool position at various locations for required assembly sequence.
- Synchronous operation. Electric tools are defined to work only when a tool is placed at correct required position, when both side operators operate the tool simultaneously & synchronously. Further if one operator finishes early, he cannot leave his tool/position till the second operator completes his work, otherwise system generates an error & stops working.
- Deskilling of operations. This unique system completely deskills the operation, thus eliminating requirement of highly skilled operators and dependency upon human skill.
- Eliminates mental fatigue. The cognitive stress built by repetition of critical operations requiring highest attention is removed by the system. Thus the system proves user friendly & easy to operate.
- It's a low cost and indigenous solution.
The technical advantages derived out of this invention are as under:
- Eliminates Operator Mistake - by ensuring assembly operations in synchronous mode only.
- Two operators are forced to work in tandem as a single unit.
- Proves a Low Cost & very effective solution where multi spindle tools cannot be used due to product designs.
- Ensures perfect results for part assembly process where sequence of assembly/ tightening is very critical for operation.
- Simple, cost effective solution with huge scope of horizontal deployment across the industry.

We claim:
1. A sequential and synchronous tightening system, during assembly operations, comprises a CPU configured to receive, code and process the data as per the given set of parameters, of input module having a bar code scanner to scan barcode on the engine, linear encoder and push button; an output module connected to the said CPU having an electrical tool with controlling function to function such that to receives data from CPU & triggers electrical tool for the operation (i.e. for bolt tightening) and accordingly provides feedback to CPU for Torque OK / Not OK.; a conditional indicators provide to said output module to function such away that to indicate various operating conditions to the operators -e.g. Tool position, Torque OK, Torque Not OK, Cycle OK etc. and a conditional indicators.
2. The system as claimed in claim 1 wherein the said electric tools in the output module are in two numbers for operation.
3. The system as claimed in claims 1 and 2 wherein the said electric tools programmed in the controller with Soft data like- various models, sequence of operation & torque values at various positions.
4. The system as claimed in claims 1 to 3 wherein the said both tools stand inoperative at any point in time such that to start the cycle, operator needs to scan the model code on engine to set the model code, sequence to be followed & torque for tightening and further if one operator finishes early, he cannot leave his tool/position till the second operator completes his work, otherwise system generates an error & stops working thus forming the both operators work as a single working unit.