Title of Invention

AN ELECTRICAL NUT RUNNER FOR USE IN AUTOMOBILE INDUSTRY

Abstract

Electrical nut runner (1) for use in automobile industry. The tool unit PLC (Programmble Logic Circuit) (3) and conveyor PLC (Programmable Logic Circuit) (8) are looped together by a relay (11) for synchronized operation thereof. This prevents the conveyor from moving further carrying any improperly tightened components to the assembly line due to negligence or otherwise of the operator and improves the reliability of the nut runner.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) COMPLETE SPECIFICATION (SEE SECTION 10; RULE 13) TITLE An electrical nut runner for use in automobile industry APPLICANTS Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400001, Maharashtra, India, an Indian company INVENTORS Under Section 28(2) Patwardhan Suhas Bhalchandra and Joshi Yashwant Anant, Tata Motors Limited, Manufacturing Division CVBU, Pimpri,Pune - 411018, Maharashtra, India, Indian nationals The following specification particularly describes the nature of this invention and the manner in which it is to be performed : FIELD OF INVENTION Electrical nut runner for use in automobile industry. PRIOR ART In automobile industry pairs of components such as cylinder block and cylinder head or connecting rod and crankshaft or crankshaft and main bearing caps or flywheel and crankshaft or flywheel and clutch may be assembled together by tightening them together with fasteners such as nuts and bolts, screws or studs in an electrical nut runner which may be single spindle or multi spindle type. An electrical nut runner comprises one tool unit or multiple tool units, as the case may be, up and down movabiy suspended overhead. Each tool unit comprises a tool head driven by a PLC (Programmable Logic Circuit) through a torque and angle controller. Pairs of components to be assembled are placed one above the other on a platform which moves with a conveyor underneath the tool unit(s). The conveyor may be continuously moving or indexing type and is driven by a PLC connected to an electric 2 motor through a normally open power contactor. When the conveyor is moving the normally open power contactor remains closed under command by the conveyor PLC. In the case of a continuously moving conveyor when the components to be tightened together reach a tightening station, the operator operates the tool unit PLC and brings down the tool unit (s) and carries out the tightening of the fasteners in the components. In the case of an indexing type conveyor at the end of predetermined intervals of time as set in the timer in the conveyor PLC, the PLC opens the power contactor and indexes or stops the conveyor at a tightening station and the operator carries out the tightening operation of the fasteners in the components as described earlier. On completion of the tightening operation the operator operates the tool unit PLC and retracts the tool unit (s) to the original position thereof and the conveyor moves to the next station. The fastener tightening cycle is thus repeated. Both the tool unit PLC and conveyor PLC operate independently and there is absolutely no synchronization of operation of the two. 3 Due to reasons such as improper threading or tapping of holes in the components there are chances of the components being not properly tightened together to the required or set torque. In case the components have not been properly tiglitened to the required or set torque the tool unit PLC senses the defect and operates an audio visual alarm to alert the operator who in turn operates the tool unit PLC to stop the tool unit(s) and retract them to the original position thereof. He also operates the conveyor PLC to stop the conveyor movement and remove the improperly tiglta Owing to negligence or otherwise in case the operator does not stop the conveyor and remove the improperly tightened components, the conveyor automatically moves to the station carrying the improperly tiglitened components to the assembly line. The joints between the aggregates or assemblies of the improperly tightened components are weak and in case such assemblies happen to be assembled into the vehicles they may fail or malfunction. The nut runner is thus not very reliable. 4 OBJECTS OF INVENTION An object of the invention is to provide an electrical nut runner for use in automobile industry which is simple in construction and very reliable. Another object of the invention is to provide an electrical nut runner for use in automobile industry which is economical. DETAILED DESCRIPTION OF INVENTION According to the invention there is provided an electrical nut runner for use in automobile industry wherein the tool unit PLC (Programmable Logic Circuit) and conveyor PLC (Programmable Logic circuit) are looped together by a relay for synchronized operation thereof. The following is a detailed description of the invention with reference to the accompanying sole Fig 1 which is a schematic layout diagram of an electrical nut runner for use in automobile industry according to an 5 embodiment of the invention. The nut runner 1 comprises four tool units each comprising a tool head 2 driven by a PLC 3 through a torque and angle controller 4. Pairs of components 5 and 6 to be assembled together are placed on a platform 7 which moves with a conveyor 7a driven by a PLC 8 through an electric motor 9. The PLC is connected to the electric motor througli a normally open power contactor 10. The tool unit PLC 3 and conveyor PLC 8 are looped together by a relay 11 for s)mchronized operation thereof as described hereinbelow. During operation of the nut runner in case the components have not been tightened properly to the required or set torque, the tool unit PLC senses the defeetand operates an audio visual alarm (not shown) in the usual manner. This will alert the operator who will in turn operate the tool unit PLC to stop the tool units and retract them to the original position thereof. Simultaneously the tool unit PLC actuates the relay 11 which will in turn actuate the conveyor PLC. On being actuated the conveyor PLC will give out a 6 command to the power contactor in the closed condition to open and switch off the electric motor and stop the conveyor. The nut runner will have to be switched on again to continue the tightening operation after the improperly tightened components are removed from the conveyor. Thus the tool unit PLC and conveyor PLC operations are synchronized to prevent the conveyor moving further carrying the improperly tightened components to the assembly line due to negligence or otherwise of the operator and to improve the reliability of the nut runner. The cost of the relay is negligible. Therefore, the nut runner of the invention is economical. The various other parts and details of the nut runner have not been illustrated and described as such are not necessary for understanding the invention. The nut runner may comprise more or less number of tool units and even one tool unit also. Such variations of the inventions are to be construed and understood to be within the scope of the invention. 7 We claim 1. An electrical nut runner (1) for use in automobile industry comprising four tool units each comprising a tool head (2) driven by a PLC (Programmable Logic Circuit) (3) through a torque and angle controller (4\ Pairs of components (5) and (6) to be assembled together are placed on a platform (7) which moves with a conveyor (7a) driven by a PLC (Programmable Logic Circuit) (8) through an electric motor (9) characterized in that the PLC is connected to the electric motor through a normally open power contactor (10) and the tool unit PLC (3) and conveyor PLC (8) are looped together by a relay (11) for synchronized operation thereof. 2. An electrical nut runner for use in automobile industry substantially as herein described with reference to Fig 1 of the accompanying drawings. Dated this l5th day of July 2003. (Karuna Goleria) of DePENNING & DePENNING Agent for the Applicants

Documents:

716-mum-2003-abstract(04-02-2004).doc

716-mum-2003-abstract(4-2-2004).pdf

716-mum-2003-cancelled pages(24-12-2004).pdf

716-mum-2003-claims(granted)-(04-02-2004).doc

716-mum-2003-claims(granted)-(4-2-2004).pdf

716-mum-2003-correspondence(24-12-2004).pdf

716-mum-2003-correspondence(ipo)-(29-9-2004).pdf

716-mum-2003-form 1(15-7-2003).pdf

716-mum-2003-form 13(20-9-2004).pdf

716-mum-2003-form 19(29-3-2003).pdf

716-mum-2003-form 2(granted)-(04-02-2004).doc

716-mum-2003-form 2(granted)-(4-2-2004).pdf

716-mum-2003-form 26(10-7-2003).pdf

716-mum-2003-form 3(15-7-2003).pdf

716-mum-2003-form 8(29-9-2003).pdf

716-mum-2003-general power of attorney(24-12-2004).pdf

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