Title of Invention

A HOB CUTTING DEVICE WITH MEANS FOR DETECTING DEFECTIVE SYNCHRONIZING RING SPAN

Abstract

A hob cutting device with means for detecting defective synchronizing ring span comprising a drivable hob, a drivable work piece such as a synchronizing ring, a drivable holding means for holding said work piece, a drivable machine slide for forward and backward movement of said work piece thereon provided with a limit switch, drive means for driving said holding means and machine slide, a fault detecting means provided with two proximity switches being fixedly mounted on said hob cutting device and a relay circuit actuatable by said proximity switches.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) COMPLETE SPECIFICATION (SEE SECTION 10, RULE 13) TITLE A hob cutting device with means for detecting defective synchronizing ring span APPLICANTS Tata Motors Limited, an Indian company of Bombay House, 24, Homi Mody Street, Hutatma Chowk, Mumbai - 400001, India Original INVENTOR Under Section 28(2) Vishant Virupaksha Tambade, C/o Tata Motors Limited, of Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400001, Maharashtra, India, an Indian national The following specification particularly describes the nature of this invention and the manner in which it is to be performed : Granted . 30-3-2005 This invention relates to a hob cutting device with means for detecting defective synchronizing ring span. This device is applicable in automobile industry for gear cutting operations. It may also be used in any other industry requiring similar operation. A hob is basically a worm with axially cut gashes across its surface for cutting surfaces. In gear hobbing the hob and the work piece which is a gear rotate continuously. As the work piece and the hob rotate continuously, the work piece moves axially across the face of the hob and the equally spaced cutting edges of the hob cut the work piece and create teeth. It is known that the gear box plays a vital function in transmitting power from the engine to the wheels, through the rear axle or the transfer case. In a synchromesh gear box, the span size of the synchronizing ring plays a crucial role in the engagement quality of the gear boxes. Gear engagement will be difficult in case the synchronizing ring span is more than the required specifications. This is normally detected only during the testing of the gear box or in the vehicle. An over size synchronizing ring results in gear engagement problems, consequent customer dissatisfaction and warranty complaints. It is also noticed that in the existing process, operator dependence is very high. The main object of this invention is to detect an oversize synchronizing ring at the cutting stage itself and before the gear is assembled and mounted in the vehicle. The hob cutting device with means for detecting defective synchronizing ring span according to this invention comprises a drivable hob, a drivable work piece such as a synchronizing ring, a drivable holding means for holding said work piece, a drivable machine slide for forward and backward movement of the work piece thereon provided with a limit switch, drive means for driving said holding means and machine slide, a fault detecting means provided with two proximity switches fixedly being mounted on said hob cutting assembly and a relay circuit actuatable by proximity switches. This invention and its method of operation will now be described with reference to the figures in the accompanying drawings, in which Fig.I is a schematic representation of the hob cutter device according to this invention. Fig. II is the relay circuit diagram of the subject invention. In Fig. I reference numeral 1 indicates the geared motor which drives the hob indicated by reference number 2. The work piece on which teeth are to be cut by the hob cutter is shown by numeral 3. This work piece is a synchronizing ring in this specific case and is mounted on a holding means 4. Machine slide for moving the work piece forward and backward is indicated by reference number 9. Reference number 10 is the forward limiting switch. Drive means 5 for driving the work piece is a geared motor. Drive means for driving the machine slide and the holding means are indicated by numerals 6 and 8 which is a hydraulic cylinder 8 driven by hydraulic powerpack 6 consisting hydraulic oil pressurized by a pump. A solenoid valve 7 is provided for controlling the movement of the hydraulic cylinder. Reference numeral 12 is the gauge which may be shifter sleeve member. Two proximity switches 13 and 14 are provided on the shifter sleeve. Relays are indicated by numerals 15 and 16 (RL1 & RL2 respectively) which get actuated when the work piece 11 after machining sits in the gauge 12. The master relay 17 (RL3) gets actuated when machined work piece is OK. Fig. II is the circuit diagram for the device according to this invention. Contacts 1 and 2 of the relay circuit closes when a synchronizing ring for detecting any defect is positioned on the holding means or fixture. Contacts 3 and 4 also close when the ring is clamped on the holding means by the application of pressure. For starting the cycle push button P1 of the hobbing machine is pressed to establish contacts between 5 and 6. This actuates contactor C1 and the hobbing cycle starts. The hobbing cutter rotates while the machine slide comes forward. The job such as a synchronizing ring also rotates at the same time when the slide comes to the maximum forward position, the limit switch 10 (El) operates. This in turn opens the contacts 7 and 8 which makes contactor dl off and the slide retracts to its original position. On completion of this operation, the job is declamped manually by pushing the button P2. Contact is established 9 and 10 which closes activating the solenoid S1. The declamped job is then kept on the gauge or the shifter sleeve. If the size and span of the synchronizing ring is normal, the ring will slide through the shifter sleeve. This in turn will activate the proximity switches which will activate the relays RL1 and RL2. The master relay 17 (RL3) will become on and the contacts 15 and 16 will close. A new cycle may then be started. In case the span of the synchronizing ring is not proper, it will not slide through the shifter sleeve. The master relay RL3 does not get actuated and the next cycle cannot start. The operator comes to know the synchronizing ring span is not of the prescribed size and removes it from the machine. The relay system is also provided with audio visual alarms to alert the operator. The hob cutting device of this invention, therefore ensures automatic inspection and avoids the possibility of producing faulty automobile gear components. Though the invention has been described herein above with reference to specific embodiments, alterations and modifications known to persons skilled in the art are within the scope of this invention and the appended claims. WE CLAIM 1) A hob cutting device with means for detecting defective synchronizing ring span comprising a drivable hob, a drivable work piece such as a synchronizing ring, a drivable holding means for holding said work piece, a drivable machine slide for forward and backward movement of said work piece thereon provided with a limit switch, drive means for driving said holding means and machine slide, a fault detecting means provided with two proximity switches being fixedly mounted on said hob cutting device and a relay circuit actuatable by said proximity switches. 2) The device as claimed in claim 1, wherein said drive means for driving the hob and the drive means for driving said work piece are two geared motors. 3) The device as claimed in claims 1 and 2, wherein the drive means for driving said holding means and the machine slide is a hydraulic cylinder having pressurized hydraulic fluid. 4) The device as claimed in claims 1 to 3, wherein said gauge is a shifter sleeve. 5) The device as claimed in claims 1 to 4, wherein said proximity switches are capable of actuating the relay connected thereto when a defective synchronizing ring is mounted on said gauge. 6) The device as claimed in claims 1 to 5, wherein said relay circuit is provided with audio visual alarms which gets actuated when defect is detected. 7) A hob cutting device with means for detecting defective synchronizing ring span substantially as herein described with reference to the accompanying drawings. Dated this 13th day of January 2004. (Karuna Goleria) of DePENNING & DePENNING Agent for the Applicants

Documents:

43-mum-2004-cancelled pages (30-03-2005).pdf

43-mum-2004-claims(granted)-(30-03-2005).doc

43-mum-2004-claims(granted)-(30-03-2005).pdf

43-mum-2004-correspondence(30-03-2005).pdf

43-mum-2004-correspondence(ipo)-(16-05-2007).pdf

43-mum-2004-drawing(30-03-2005).pdf

43-mum-2004-form 1(14-01-2004).pdf

43-mum-2004-form 19(10-02-2004).pdf

43-mum-2004-form 2(granted)-(30-03-2005).doc

43-mum-2004-form 2(granted)-(30-03-2005).pdf

43-mum-2004-form 3(14-01-2004).pdf

43-mum-2004-form 8(10-02-2004).pdf

43-mum-2004-power of attorney(17-09-2004).pdf

abstract1.jpg