The present invention relates to a cost-effective machine for gear manufacturing process that reduces the production cost, improves productivity and production time. More particularly, the present invention relates to a machine that simultaneously performs chamfering, deburring and pre-shaving operation of a work piece without changing the work piece position.

BACKGROUND OF THE INVENTION
Gear manufacturing refers to the making of gears as per specifications required, including but not limited to specific dimensions, shapes, surface texture, contour and angle of blades/teeth. Depending on the requirements, gears can be manufactured by a variety of processes, including casting, forging, extrusion, powder metallurgy, and blanking. The machining is applied to achieve the final dimensions, shape and surface finish on the gear. The gears are forged from steel and machined to achieve desired dimensions. The initial operations that produce a semi-finishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining is called a gear blank. The gear blank then undergoes gear shaping. For gear shaping, a cutter called a form cutter travels axially along the length of the gear tooth at the appropriate depth to produce the gear tooth. After each tooth is cut, the cutter is withdrawn, the gear blank is rotated, and the cutter proceeds to cut another tooth. The process continues until all teeth are cut. With hobbing process, the shaped gear blank is machined through gear hobbing in which gear teeth are progressively generated by a series of cuts with a helical cutting tool and the gear work piece is obtained. All motions in hobbing are rotary, and the hob gear blank rotate continuously until all teeth are cut.
After gear hobbing, the gears need to be chamfered and deburred with a controlled process for the reasons such as excessive carburizing leads to hardening of tooth edges that makes edges more prone for breakage and chip off during operation leading to gear damages; burrs shipped off during operation may result in consequential damages to other gears, shafts and bearings etc.; and burrs affect subsequent gear finishing process and affects tool life during operations etc.
Chamfering is known as sharp edge removal process of gear teeth by pressing operation so the teeth material does not chip off/bulge. In the chamfering process, burrs are generated which are cleaned by de-burring process. In state of the art, the de-burring cutter comprises of a disc on the cutting edge for matching with the work piece and a proximity sensor is attached with de-burring cutter; if the de-burring cutter is not placed at the slot on work piece, then machine will not start. While, in chamfering cutter there is no such slot. Chamfering cutter module and job module should be same otherwise chamfering cutter is prone to breakage. The sequence of process at chamfering and deburring stage works as: pressing of cycle start button, clamping of fixture cap, operating the chamfering cutter and deburring cutter, starting the cycle and rotating of gear in clockwise and anti-clockwise direction, removing of gears and taking up for shaving/grinding on different machine.
After chamfering and deburring, in the next stage, either there is shaving or grinding process on the gear for finishing as per the customer specification. Gear grinding is a more precise operation to produce fine quality of gears but at the same time cost of operation is higher compared to shaving. In a work piece, generally excess material is present known as burrs, the shaving cutter/grinding wheel has to first remove excess material at edges, after the plus size is removed then the cutter/wheel performs shaving/grinding operation to make the gear of a desired size and specification. Such operations cause significant reduction in life of shaving cutter/grinding wheel.
The gear shaving is a gear finishing process in which shaving cutter receives motion from motor and drives the work piece fitted on a freely moving shaft. The shaving process removes small amount of metal from working surface of gear teeth to correct the errors in index, tooth profile and helix angle. There are various losses during the shaving/grinding process such as productivity loss that removes the plus size, reduction in tool life due to excess material removal on edges and quality loss due to tool bluntness after performing the shaving/grinding on certain work pieces.
CN202271266 discloses a one-circle two-grinding chamfering deburring machine, which is turned on and started. The upper grinding head motor drives the upper grinding belt to rotate horizontally by driving the upper active drum; the lower grinding head motor actively drives the lower. The drum drives the lower abrasive belt to rotate horizontally. When the deburred work piece passes through the channel formed by the active feeding roller row and the upper abrasive belt, the upper abrasive block fixed on the upper abrasive belt is rotated once every time the upper abrasive belt rotates. Under the action of the upper grinding belt pressing wheel group, the upper abrasive block is in elastic contact with the surface of the work piece and driven by the upper grinding head motor and the upper active drum, the polishing and deburring of the front surface of the work piece is completed twice. The lower grinding belt is driven by the lower grinding head motor and the lower driving drum for one revolution. The abrasive block on the lower grinding belt is elastically in contact with the surface of the work piece under the pressing force of the lower grinding belt pressing wheel group. Driven by the lower grinding head motor and the lower driving drum, the polishing and deburring of the back of the work piece is completed twice. The main drawback of the invention is that the operation of deburring, chamfering and grinding is not done simultaneously which increases the duration of gear manufacturing.
US7377731 discloses a work piece having edges comprising teeth, slots, dovetail, keyway or other irregularly shaped artifacts, can be provided with a uniform chamfer around the periphery of the work piece by bringing a grinding wheel or cutter in one single down feed at indexed intervals. The shape or profile of the grinding wheel or cutter is formed from an algorithm depending on the shape and dimensions of the work piece artifacts, such as gear teeth, etc., to provide the uniform chamfer at each slot of, for example, an internal or external gear wheel. A method of providing such a chamfer on irregularly shaped artifacts comprises forming a gear grinding wheel from the dimensions of the desired chamfer, and providing a chamfering tool or grinding wheel in accordance with an algorithm desired for the required chamfer, then bringing the gear chamfering tool in proximity to, and in contact with the edges of the work piece so as to produce a uniform chamfer on the sides and back edge. The method may include a step of moving of the cutter or grinding wheel from one side to another and tilting the cutter or grinding wheel to chamfer the back side. The main drawback of the invention is that the grinding is done by the grinding wheel or button disposes at the end of rotating spindle and the desired bevel is done to the gear manually and the operations are done at different gears at different time.
JP2013505844A discloses a gear processing machine, such as a gear cutting machine or a gear grinding machine, which includes a chamfering and/or deburring device and an auxiliary spindle on the same machine. A transfer mechanism may be used to charge, unload and transfer work pieces between the machining spindle and the auxiliary spindle, thereby simultaneously performing a cutting, chamfering and/or deburring process. While another gear is being machined on the machining spindle, the completed work piece is removed from the machine via the auxiliary spindle and the raw work piece is loaded into the machine, thereby increasing the productivity of the machine and creating a more efficient operation. The main drawback of the invention is that an additional spindle is required to perform the grinding operation that is a time consuming process.
Therefore, there is a need to develop a device that reduces the above losses and helps in operating the processes using fewer machines set up.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a machine that simultaneously performs chamfering, deburring and pre-shaving operation on a gear work piece which improves production.
Another object of the present invention is to provide a machine that provides a continuous synchronization of the three processes of chamfering, deburring and pre-shaving.
Yet another object of the present invention is to provide a cost-effective machine that saves the production cost, improves productivity by reducing the production time and usage, without compromising quality of gears.
Still another object of the present invention is to provide a sliding mechanism for pre-shaving in a machine to perform the three processes simultaneously.

SUMMARY OF THE INVENTION
The present invention provides a machine having an arrangement that eliminates the chances of chamfer bulging that occurs frequently while machining the gear work piece and reduces the overall cost and increases the productivity and tool life.
In a main embodiment, the present invention provides a machine for chamfering, deburring and pre-shaving of a gear work piece simultaneously wherein the device comprises of a machine bed, a chamfering tool, a deburring tool, a pre-shaving tool. Said machine has an arrangement having a chamfering tool in x-axis plane with reference to the machine bed, a deburring tool in z-axis plane with reference to the machine bed and a pre-shaving tool inclined at a predefined angle from the x-axis plane with reference to the machine bed. The chamfering, deburring and pre-shaving of the gear work piece is done simultaneously on said machine without changing the position of work piece.
The machine performs an automatic operation of work piece without the requirement of special jigs, fixtures and extra machining. The machine thus eliminates the manpower cost and leads to increased productivity, increased tool life and reduction of production time and usage.

BRIEF DESCRIPTION OF THE DRAWING
An understanding of the present invention may be obtained by reference to the following drawings:
Figure 1 shows a schematic diagram of the machine in accordance with the present invention.
Figure 2 shows a magnified view of the chamfered & deburred gear work piece in accordance with the present invention.
Figure 3(a) shows a schematic diagram of pre-shaving tool engaged in the gear work piece and its magnified view in accordance with the present invention.
Figure 3(b) shows another schematic diagram of the pre-shaving tool engaged with the gear work piece in accordance with the present invention.
Figure 4 shows a front view of the chamfering tool engaged in the gear work piece in accordance with the present invention.
Figure 5 shows a front view of the deburring tool engaged in the gear work piece in accordance with the present invention.
Figure 6 shows a front view of the pre-shaving tool engaged in the gear work piece in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The present invention provides a cost-effective machine for gear manufacturing process. The machine includes an arrangement having a sliding pre-shaving tool with a chamfering tool and a deburring tool. The simultaneous operations of chamfering, deburring and pre-shaving are performed on the machine without changing the work piece position.
The present invention comprises a modification in existing setup to introduce third operation of secondary deburring or pre-shaving of gears on existing machine. This innovation results in significant saving in production cost by using same resources of conventional setup, improved productivity by significant reduction in production time.
Gear shaving is a gear finishing operation which removes small amount of metals i.e., burs from the active surface of the gear teeth. Its purpose is to remove the bulging on teeth introduced during gear chamfering. It is necessary that if burs chip off from teeth during operation it may damage other gear, shaft, bearings etc. Therefore, in order to increase the productivity & changing the paradigm of gear manufacturing without compromising in quality the solution is proposed that reduces the overall cost of production while maintaining the desired specification of the quality standards. The present invention enables a pre-shaving operation to remove excess material generated during chamfering process without disturbing the setup.
In general, for automotive applications, gears are forged from steel and machined to achieve desired dimensions. The initial operations that produce a semi-finishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining is called a gear blank. The process initiates with gear shaping, wherein, the cutter called a form cutter travels axially along the length of the gear tooth at the appropriate depth to produce the gear tooth. After each tooth is cut, the cutter is withdrawn, the gear blank is rotated, and the cutter proceeds to cut another tooth. The process continues until all teeth are cut.
Gear shaping is followed by gear hobbing which is a machining process in which gear teeth are progressively generated by a series of cuts with a helical cutting tool. All motions in hobbing are rotary, and the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.
Hobbing is followed by chamfering and deburring process which is a controlled process. Additional care and control is required during chamfering and deburring as excessive carburizing leads to hardening of tooth edges. This makes edges more prone for breakage and chip off during operation leading to gear damages. Burrs shipped off during operation may result in consequential damages to other gears, shafts and bearings etc. Burrs also affect subsequent gear finishing process and affect tool life etc.
Chamfering is sharp edge removal processes of gear teeth by pressing operation, so the teeth material does not chip off/bulge. In the chamfering process, burr is generated which is cleaned by de-burring process simultaneously. De-burring cutter provides with a disc on the cutting edge for matching with the work piece and a proximity sensor is attached with de-burring cutter; if the de-burring cutter is not placed at the slot on work piece, then machine will not start. In chamfering cutter there is no such slot. Chamfering cutter module and job module should be same otherwise chamfering cutter may break.
After chamfering and deburring, in the next stage, either there is shaving or grinding process on the gear for finishing as per the desired specification. Gear grinding is a more precise operation, produce fine quality of gears but at the same time cost of operation is higher compared to shaving. Due to teeth plus size than base size on edges, shaving cutter wheel has to first remove excess material at edges, after the plus size is removed which causes significant reduction in shaving cutter wheel life. Gear shaving is gear finishing process in which shaving cutter receives motion from motor and drives the work piece which is coupled onto a shaft moving freely. Shaving process removes small amount of metal from working surface of gear teeth to correct the errors in index, tooth profile and helix angle.
In a main embodiment, the present invention provides an improved gear processing machine for chamfering, deburring and secondary deburring or pre-shaving of a gear work piece simultaneously wherein the device comprises of a machine bed, a chamfering tool, a deburring tool, a pre-shaving tool. Said machine has an arrangement having a chamfering tool in x-axis plane with reference to the machine bed, a deburring tool in z-axis plane with reference to the machine bed and a pre-shaving tool inclined at a preferred predefined angle of 45 degrees from the x-axis plane with reference to the machine bed. Hence, the deburring tool and the chamfering tool are positioned in a three-coordinate plane with reference to the machine bed. The chamfering, deburring and pre-shaving of the gear work piece is done simultaneously on said apparatus/machine without changing the position of work piece. The pre-shaving tool includes but is not limited to serration type burr removing cutter that is made of a material including the HSS and D2 grade of high-speed steel as per ASTM A681-87a. The machine has a cycle time ranging from 6-10 seconds and the life cycle of the shaving tool ranges from 50,000-60,000 pieces per tool.
Now referring to Figure 1, the present invention provides the machine for performing chamfering/deburring and pre-shaving operation in gear manufacturing process. The machine 100 comprises of a machine bed 5, a chamfering tool 2, a deburring tool 1, a pre-shaving tool 4 and a work piece 3. The machine 100 has an arrangement wherein the deburring tool 1 is positioned in z-axis plane with reference to the machine bed 5; the chamfering tool 2 is positioned in x-axis plane with reference to the machine bed 5 and the pre-shaving tool 4 is positioned at an angle of 45 degrees from the x-axis plane. The machine performs the three processes of chamfering, deburring and pre-shaving simultaneously without changing the work piece position, thus saving the total time spent in gear manufacturing. The machine provides an arrangement that eliminates the chances of material bulging on edges of teeth of gear that occurs frequently while machining the work piece. In a preferred embodiment of the present invention a sliding mechanism is introduced having shaving tools at its one end. The sliding mechanism is mounted on an existing two-way machine to arrive at the concept depicted in Figure 1. Once gear has undergone chamfering and de-burring operations, the pre-shaving tools slide perform operation without changing the work piece position. Therefore, additional slide provided on the same chamfer machine and pre-shaving cutter is mounted on it, so that the excess material is removed on the chamfering/deburring stage itself by same operator at same machine and fixtures.
Table 1 provides the estimation of tool life and costing factor of the machine performing the three processes.

Table 1
Tool life and costing factor of the machine
Factors State of the Art Machines Present Invention
Life cycle of shaving tool 3500 pieces per tool 7000 pieces per tool
Cycle time 15 seconds 07 seconds

A conventional machine set up having chamfering and deburring tool has an average life cycle of 3500 pieces per tool of grinding wheel with a cycle time of 15 seconds. The machine in the present invention with chamfering, deburring and shaving/grinding tools has a life cycle of 7000 pieces per tool and a cycle time of 7 seconds. The cost of procuring, installing and settling cost of the machine is low. It does not require special jigs and fixtures while subsequent operations. It increases the tool life, productivity, reduces the material handling cost, frequency of error and fault. It also saves the manpower and produces the high level of gears with single operator accountability.
Now referring to Figure 2, a magnified view of the gear work piece is shown. Work piece 3 is having a material bulge portion. The work piece 3 is chamfered using the chamfering tool 2. In chamfering, sharp edge removal process of gear tooth is carried out by pressing operation in a manner such that the tooth material does not chip off or bulge.
During chamfering, burrs are generated on the outer as well as inside edges of the tooth of the gear work piece. Burrs on the outside edges are removed while deburring. The deburring tool 1 depends on the type of gear work piece 3 that includes but not limited to spur gear, dog teeth gear, bevel gear. However, burrs on inside edge are removed while pre-shaving operation. Conventionally, excessive carburizing for gear shaping leads to hardening of the burrs that causes damage to the shaving tool and reduces the life of shaving tool. Hence, before reducing the size of tooth to the base size as per specification of the gear, the excess material i.e. burrs on inside edges are removed first.
Now referring to Figure 3(a), a schematic diagram of pre-shaving tool 4 engaged in the gear work piece 3 and its magnified view are shown. The work piece 3 having a material bulge on its inside edge is depicted. The bulge appears after chamfering and deburring and is removed through the pre-shaving tool 4. For removal of the burrs, the gear work piece 3 is rotated against the direction of pre-shaving tool 4 and the bulges are removed in the form of dust as the work piece 3 is shaved/trimmed. The pre-shaving tool 4 is a serration type burr cutter and removes the inside burr as depicted in the magnified view.
Now referring to Figure 3(b), another schematic diagram of pre-shaving tool 4 engaged in the gear work piece 3 is shown. To ensure complete removal of the burrs, the gear work piece 3, after rotating against the direction of pre-shaving tool 4 is made to rotate in the direction towards the pre-shaving tool 4. The bulges are removed in the form of dust and the work piece 3 is pre-shaved/trimmed.
Now referring to Figure 4, a front view of the chamfering tool engaged in the gear work piece in accordance with the present invention is illustrated in which the gear work piece 3 after chamfering have the burr on the teeth of the gear work piece 3. Referring to Figure 5, a front view of the deburring tool 1 engaged in the gear work piece in accordance with the present invention is illustrated in which the gear work piece 3 has no burr on the teeth. The deburring tool used in the gear processing machine depends on the type of gear which is being processed such as a spur gear, dog teeth gear, bevel gear and alike. In an exemplary embodiment, the improved gear processing machine being used for processing a dog teeth gear uses a dog-teeth deburring cutter. The secondary deburring tool or pre-shaving tool is engaged with the gear workpiece 3, the deburring tool 1 slides into the initial position and the secondary slides towards the gear work piece 3 and match with dog teeth for removing the burr from the dog teeth. Referring to Figure 6, a front view of the pre-shaving tool 4 engaged in the gear work piece 3 in accordance with the present invention is illustrated.
Therefore, the present invention provides a machine which decreases the inventory of grinding tools and overhead cost, reduces the frequency of error and fault, reduces material handling cost and risk of damages. The machine which operates chamfering, deburring and pre-shaving simultaneously without changing the work piece position.
The present invention is advantageous as the procurement, installation and settling cost of shaving mechanism is very low. No special jigs and fixture are required while integration of subsequent operations for machining. No extra machine and manpower required before delivering the gear for next operation. The present invention increases the tool life of grinding machine. The improved machine increases the productivity as non-productive activities get eliminated (i.e., machine setting and tool changing)
Inventory of grinder tools has been reduced which directly decreases the inventory & overhead cost. As it is an automation system frequency of error & fault reduces accordingly. Material handling cost & risk of damages (i.e., dent or swelling on gear) are also reduced. Removal of very sharp burs reduces the risk of tool handling injuries. Single operator accountability for enhanced productivity and quality, higher productivity of gears etc. are among other advantages.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

We claim:

1.An improved gear processing machine (100), comprising:

a machine bed (5) with a fixture to load a workpiece (3);

a chamfering tool (2) for chamfering process; and

a deburring tool (1) for deburring process;

wherein,
said improved gear processing machine (100) further comprises a pre-shaving tool (4) for excess material removal process generated during chamfering process;

said pre-shaving tool (4) is inclined at a predefined angle from x axis plane with reference to said machine bed (5);

said work piece (3) is chamfered using said chamfering tool (2), deburred by said deburring tool (1) and pre-shaved by said pre-shaving tool (4) on said gear processing machine (100) without changing position of said work piece (3);

said machine bed (5) is having an additional slide with pre-shaving tool mounted on it for removing excess material removal generated during chamfering process;

said work piece (3) is rotated against direction of pre-shaving tool (4) for removing said excess material and said work piece (3) is then rotated towards said pre-shaving tool (4) for ensuring complete removal of said excess material; and

said improved gear processing machine (100) reduces manpower cost and leads to increased productivity, increased tool life and reduction of production time and usage.

2. The improved gear processing machine (100) as claimed in claim 1, wherein said chamfering tool (2) is positioned in x-axis plane with reference to the machine bed (5).

3. The improved gear processing machine (100) as claimed in claim 1, wherein said deburring tool (1) is positioned in z-axis plane with reference to the machine bed (5).

4. The improved gear processing machine (100) as claimed in claim 1, wherein said predefined angle ranges from 40 to 45 degree.

5. The improved gear processing machine (100) as claimed in claim 1, wherein said work piece (3) is a gear work piece.

6. The improved gear processing machine (100) as claimed in claim 1, wherein said deburring tool (1) depends on type of gear being processed from said work piece (3) and includes but not limited to spur gear, dog teeth gear, bevel gear.

7. The improved gear processing machine (100) as claimed in claim 1, wherein said pre-shaving tool (4) includes but is not limited to a serration type burr removing cutter that is made of a material including but not limited to HSS and D2 grade of high-speed steel as per ASTM A681-87a.

8. The improved gear processing machine (100) as claimed in claim 1, wherein said improved gear processing machine (100) ensures cycle time ranging from 6-10 seconds and the life cycle of the shaving tool (4) ranges from 50,000-60,000 pieces per tool.