DESC:FIELD OF THE INVENTION
[0001] This invention relates to the field of mechanical engineering. Particularly, this invention relates to the field of forging. More particularly, the present invention relates to a die repair process used in closed die forging process.

[0002] Specifically, this invention relates to a system and method for opening a forging die cavity, uniformly, during a die repair process using a CAM program.

BACKGROUND OF THE INVENTION
[0003] Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer or a press. Forging is often classified according to the temperature at which it is performed: cold forging (a type of cold working), warm forging, or hot forging (a type of hot working). For the latter two, the metal is heated, usually in a furnace.

[0004] During the closed die forging operation, due to friction forces between a forging die and a material being forged, the surface of the forging die wears out. Due to this ‘wear’ phenomenon, shape of the forging die cavity gradually changes.

[0005] When this ‘wear’ of the die becomes substantial, the die(s) has to be taken out of production for repair. Repair of the worn-out forging die goes through the following process steps:
- Material is removed from the die cavity uniformly (also called opening of die cavity) throughout the impression;
- Welding is filled in throughout this opened cavity upto a required depth;
- Machining is done to achieve the original shape of the die cavity or die impression.

[0006] Each of the process steps has its own cycle time. The overall cycle time required to repair the die is aggregate of all these three cycle times. The total time required to repair the die is important as it dictates the time required to bring the die back for production. Longer repair times may lead to the production equipment’s (forging presses) to remain idle. Thus, the die repair time has a direct bearing on the productivity of the forging shop.

PRIOR ART
[0007] The method of material removal before welding has significant effect on a die repair process cycle time and quality. Conventionally, one of the following three methods was used for removing the material from the worn out die surface (i.e. to open the die cavity):
[0008] Gouging method:
[0009] Figure 2 illustrates this gouging method. Gouging is a metal removing process which requires special purpose electrodes with thick flux coating to generate strong arc force and gas stream. By creating an electric arc between the electrode and die surface, high degree of heat is generated which melts the die surface locally. This molten material is then removed using high pressure air or gas which is used during the process. Thus, gouging process is characterized by large amount of gas being generated to eject molten metal.

[00010] Though gouging is typically used for the removal of material from the surface of the worn out die, it has certain disadvantages such as:
- Gouging is a manual process which is performed by human being and thus the performance depends upon skill of an operator. The amount of material being removed from the worn out die surface is not precise and manual error is likely to be present.
- As the process is manual, cycle time is also very large.
- Special purpose electrode is required for performing this process.
- Gouged Surface produced is very rough in nature.
- Dimensional control on the Gouging area is difficult.
- Gouging is a very complicated process from ergonomics point of view.
- This process is known to cause pollution in the atmosphere and poses risk to health of operator.

[00011] Step Down method:
[00012] Figure 3 illustrates this Step Down method. In the Step Down method, a CAD model of the forging die (19) is used for generating a CAM program. But, in order to open the die cavity, instead of using tool(s) as defined in the CAM program, a larger diameter tool is used to open the die cavity according to requirement. Further, during machining of dies, the tool has to be taken down step by step in Z axis direction to go to the desired depth gradually. The step down method though found to be better compared to the manual gauging method, it has certain drawbacks:
- Need to consider minimum corner radius and accordingly decide diameter of the tool based on amount of opening.
- Chances of tool breakage are high while retracting from one portion to another.
- It is a time consuming method.
- Requires manual interference to reach desired die cavity opening depth.
- Requires supervision.
- A separate tool is required for machining operation used for die cavity opening depending upon opening amount.

[00013] CAD offset method.
[00014] Figure 4 illustrates this CAD offset method. The CAD Offset Model Method is a method which involves use of CAD software to create a 3D model which has uniformly opened Die cavity. The die cavity is opened in the model by an offset method. Thus, in this process the CAD modeler starts with a CAD model of the forging die (19) and then systematically offsets the surfaces of the die cavity (10) by required amount. In a complex shaped forging die this process cannot be done in one command and hence, requires lot of work by the CAD modeler. Once the model is ready after this offset process, the CAM program is generated from this new model which is then used for machining of the worn out die. The disadvantages of CAD offset method are listed below:
- This is a time consuming method. The time required to make the offset model depends on the geometry involved.
- Manual interference is required. This may lead to costly manual errors.
- Need to create CAD model and drawing separately.
- Need to maintain data and dependency is involved.
- Use of software means incurring cost in terms of man hour cost and software’s per hour usage cost.

OBJECTS OF THE INVENTION
[00015] An object of the invention is to provide a system and method for repairing / re-building a die for forging once it’s worn out.

[00016] Another object of the invention is to provide a system and method for repairing / re-building a die for forging once it’s worn out with a substantial saving in time.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
[00017] Figure 1a illustrates a cross section of a die (19) having a die cavity (10).
[00018] Figure 1b illustrates a wear (12) in this die cavity (10) after forging run.
[00019] Figure 1c illustrates a uniformly opened die cavity (20) which is ready for welding.
[00020] Figure 2 illustrates the flow chart for gouging method of the prior art.
[00021] Figure 3 illustrates the flow chart for Step Down method of the prior art.
[00022] Figure 4 illustrates the flow chart for the CAD offset method of the prior art.
[00023] Figure 5 illustrates the flow chart of the method of opening the die cavity according to one embodiment of the present invention.
[00024] Figure 6 shows the schematic diagram of the system used to perform the method according to the present invention.

SUMMARY OF THE INVENTION
[00025] In accordance with the present invention there is provided a system and a method for opening a forging die cavity (10). The method comprising the following steps:
a. Taking or generating CAD model (1) of a forging die (19) with cavity that is to be repaired / rebuilt;
b. generating a first CAM program (2) of the forging die using a CAM program generation module;
c. importing the first CAM program (2) of the forging die in a machining process simulation module;
d. virtually cutting / machining a virtual blank stock with a larger diameter cutter based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), using a larger diameter tool in the machining process simulation module;
e. obtaining geometrical parameters of the modified simulated output (3) using machining process simulation module;
f. importing the geometrical parameters of the modified simulated output (3) into a CAM program generation module;
g. generating a second CAM program (4) of the modified geometry-based simulated output (3), in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program (4);
h. providing an input of second CAM program (4) which can be directly run on a CNC machine (18) to open die cavity uniformly of forging die (19), in a desired manner as per requirement to obtain the forging die with uniformly open cavity (20).

[00026] There is also provided a system (50) for opening a forging die cavity, said system comprises a CAD station (12), a CAM station (14), a simulation station (16), and a CNC machine (18), wherein a CAD model (1) of a forging die (19) with cavity (10) to be repaired is generated from the CAD station (12) and transferred to the CAM station (14), a first CAM program (2) is being generated using a CAM program generation module from the CAM station (14) which is imported into a machining process simulation module in the simulation station (16), wherein a virtual blank stock is virtually cut / machined using a larger diameter cutter based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), in the machining process simulation module, wherein the modified geometry-based modified simulated output (3) are imported into a CAM program generation module wherein a second CAM program (4) of the modified geometry-based simulated output (3) is generated, in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program(4), wherein an input of second CAM program (4) is provided and directly run on a CNC machine (18) to open die cavity uniformly of forging die (19), in a desired manner as per requirement to obtain the forging die with uniformly open cavity (20).
DESCRIPTION OF THE INVENTION
[00027] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[00028] According to this invention, there is provided a system and method to open a forging die cavity (10).

[00029] Example embodiments will now be described more fully with reference to the accompanying drawings. The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[00030] It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[00031] In one exemplary embodiment, Figure 5 illustrates the process steps of this invention.

[00032] In at least an embodiment of this invention, the process involves a first step (101) of generating CAD model (1) of a forging die (19) with cavity using 3D CAD Generation module. If the CAD model already exits then it is modified as per requirement using 3D CAD Generation module

[00033] In at least an embodiment of this invention, the process involves a second step (102) of generating a first CAM program (2) for the cavity (10) of the forging die (19)from the said CAD model (1)using a 3-dimension CAM Program generation module.

[00034] In at least an embodiment of this invention, the process involves a third step (103) of importing the generated first CAM program (2) of cavity (10) of the forging die (19) in a machining process simulation module.

[00035] In at least an embodiment of this invention, the process involves a fourth step (104) of using a larger diameter tool in the machining process simulation module in order to virtually cut / machine a virtual blank stock with a larger diameter cutter, based on the amount of opening required, to obtain a modified geometry-based modified simulated output (3).

[00036] In at least an embodiment of this invention, the process involves a fifth step (105) of using machining process simulation module to obtain geometrical parameters of the modified simulated output (3).

[00037] In at least an embodiment of this invention, the process involves a sixth step (106) of importing the geometrical parameters of the modified simulated output (3) into a CAM program generation module.

[00038] In at least an embodiment of this invention, the process involves a seventh step (107) of generating a second CAM program (4) from the modified geometry-based simulated output (3), in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program (4).

[00039] In at least an embodiment of this invention, the process involves an eighth step (108) of providing an input of second CAM program (4) which can be directly run on a CNC machine to open die cavity uniformly of forging die (19), in a desired manner as per requirement. The final output after the run on CNC machine is forging die with uniformly open cavity (20).

[00040] In one preferred embodiment, the method for opening a forging die cavity (10) comprising the following steps:
- Taking/generating CAD model (1) of a forging die (19) that is to be repaired / rebuilt using 3D CAD Generation module;
- generating a first CAM program (2) of the forging die with cavity using a CAM program generation module;
- importing the first CAM program (2) of the forging die with cavity in a machining process simulation module;
- virtually cutting / machining a virtual blank stock with a larger diameter cutter/tool based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), in the machining process simulation module;
- obtaining geometrical parameters of the modified simulated output (3) using machining process simulation module;
- importing the geometrical parameters of the modified simulated output (3) into a CAM program generation module;
- generating a second CAM program (4) of the modified geometry-based simulated output (3), in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program (4) using CAM program generation module;
- providing an input of second CAM program (4) which can be directly run on a CNC machine to open die cavity uniformly of forging die (19), in a desired manner as per requirement to obtain forging die with uniformly open cavity (20).

[00041] Typically, the step of taking/generating the CAD model (1) of a forging die (19) is carried out using 3D CAD Generation module at a CAD station (12).

[00042] Typically, the step of generating a first CAM program (2) using a CAM program generation module is carried out at a CAM station (14).

[00043] Typically, the step of importing the first CAM program (2) of the forging die (19) in a machining process simulation module is carried out at a simulation station (16) on which machining process simulation module is present.

[00044] Typically, the step of virtually cutting / machining a virtual blank stock with a larger diameter cutter is carried out at a simulation station (16) using machining process simulation module. This virtual cutting produces a simulated geometric output of a forging die with opened die cavity (20).

[00045] In one aspect there is also provided a system (50) for opening a forging die cavity (10), said system comprises a CAD station (12), a CAM station (14), a simulation station (16), and a CNC machine (18), Said system is illustrated in Figure 6. A CAD model (1) of a forging die with cavity (19) to be repaired is generated from the CAD station (12) and transferred to the CAM station (14). A first CAM program (2) is generated from said CAD Model (1) using the CAM station (14) which is imported into a machining process module in the simulation station (16). A virtual blank stock (not shown) is virtually cut / machined using a larger diameter cutter (not shown) based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), using a larger diameter tool in the machining process simulation module. The geometrical parameters of the modified simulated output (3) are obtained using machining process simulation module. These geometrical parameters of the modified simulated output (3) are imported into a CAM program generation module. Again a second CAM program (4) of the modified geometry-based simulated output (3) is generated, in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program (4). Finally, an input of second CAM program (4) is provided which directly run on a CNC machine (18) to open die cavity uniformly of a forging die (19), in a desired manner as per requirement. The final output after the run on CNC machine is forging die with uniformly open cavity (20).

[00046] The following advantageous results were observed:
- User can control opening area for welding using CAM program.
- No need to take the cutter down to overcut impression; time is saved remarkably.
- No tool breakage as excessive load on the tool or digging in left-out stock is avoided.
- This method is useful for thermal fusion coating process where die opening in uniform manner is a basic requirement.
- CAD Modeling time eliminated
- Special machines or special tools are not required. This system and method can run on old machines using existing tools.
- Consistency in results is assured.
- Operator involvement to is less, hence manual errors are reduced.
- No ergonomics issue.
- Safe practice. No risk involved.
- Virtual stock model can be used for Robotic welding as an input.
[00047] The TECHNICAL ADVANCEMENT of this invention lies in providing a system and method which uses a 3-dimension CAD generation module, CAM program generation module and a machining process simulation module in a co-ordinated manner. Furthermore, this system and method uses an innovative step-wise combination of: a) 3D CAD modeling; b) CAM programming; c) Machining simulation; and d) again, CAM programming to achieve a uniformly open forging die cavity which is further used to produce repaired / rebuilt forging die.

[00048] Although this specification describes this invention in relation to hot forging die, it is to be understood that the same invention, without departing from its inventive concept, can be used in cold forging dies as well as in warm forging dies. Further this method of die repair can be used for any applications where dies or moulds are used like casting, Metal Injection Moulding etc.

[00049] While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
,CLAIMS:We Claim:
1. A method for opening a forging die cavity (10); said method comprising the following steps:
a) Taking or generating CAD model (1) of a forging die (19) with cavity that is to be repaired / rebuilt;
b) generating a first CAM program (2) of the forging die using a CAM program generation module;
c) importing the first CAM program (2) of the forging die in a machining process simulation module;
d) virtually cutting / machining a virtual blank stock with a larger diameter cutter based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), using a larger diameter tool in the machining process simulation module;
e) obtaining geometrical parameters of the modified simulated output (3) using machining process simulation module;
f) importing the geometrical parameters of the modified simulated output (3) into a CAM program generation module;
g) generating a second CAM program (4) of the modified geometry-based simulated output (3), in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program (4);
h) providing an input of second CAM program (4) which can be directly run on a CNC machine (18) to open die cavity uniformly of forging die (19), in a desired manner as per requirement to obtain the forging die with uniformly open cavity (20).

2. The method as claimed in claimed 1, wherein the step of taking or generating the CAD model (1) of a forging die (19) with cavity is carried out using a 3-dimension CAD generation module at a CAD station (12).

3. The method as claimed in claim 1, wherein the step of generating a first CAM program (2) of the CAD model (1) of forging die with cavity is carried out using a CAM program generation module at a CAM station (14).
4. The method as claimed in claim 1, wherein the step of importing the first CAM program (2) of CAD model (1) of the forging die with cavity in a machining process simulation module is carried out at a simulation station (16).

5. The method as claimed in claim 1, wherein the step of virtually cutting / machining a virtual blank stock with a larger diameter cutter is carried out at a simulation station (16).

6. A system (50) for opening a forging die cavity, said system comprises a CAD station (12), a CAM station (14), a simulation station (16), and a CNC machine (18), wherein a CAD model (1) of a forging die (19) with cavity (10) to be repaired is generated from the CAD station (12) and transferred to the CAM station (14), a first CAM program (2) is being generated using a CAM program generation module from the CAM station (14) which is imported into a machining process simulation module in the simulation station (16), wherein a virtual blank stock is virtually cut / machined using a larger diameter cutter based on the amount of opening required to obtain a modified geometry-based modified simulated output (3), in the machining process simulation module, wherein the modified geometry-based modified simulated output (3) are imported into a CAM program generation module wherein a second CAM program (4) of the modified geometry-based simulated output (3) is generated, in that, the virtually cut stock is taken as output from the machining process simulation module and is again used for generating a second CAM program(4), wherein an input of second CAM program (4) is provided and directly run on a CNC machine (18) to open die cavity uniformly of forging die (19), in a desired manner as per requirement to obtain the forging die with uniformly open cavity (20).

Dated this 15thday of March, 2020

CHIRAG TANNA
Of NOVO IP
APPLICANT’S PATENT AGENT