DESC:TECHNICAL FIELD
[001] The embodiments herein generally relate to rockshaft in vehicles and more particularly, but not exclusively to a method of manufacturing hollow rockshaft being assembled to a lift housing of vehicles.
BACKGROUND
[002] Generally, a rockshaft is a component used in a lift housing assembly of a vehicle for mounting or supporting the lift arms of a three point hitch of the vehicle. A known art discloses a lifting rock shaft connected to the rear axle structure of the tractor for rockable movement and the rock-shaft includes an arm means adapted for independent movement and connected to the working tool. On the rockable structure there is provided an abutment arm adapted to engage the underside of the arm means to impart lifting movement to the working tool means. Also, on this same rock-shaft is journaled an adjusting lever adatped to cooperate with the arm means for limiting the downward movement of the working tool. The rock-shaft, the arm means, and an adjustable lever are carried by the same supporting structure which is in turn adapted to be attached to the rear axle structure of the tractor. The adjusting lever works over a quadrant which is attached to the same supporting structure. The rock-shaft is rocked by a single acting fluid actuated cylinder device which is also supported with the various parts so arranged, the entire assemblage including the adjustable stop means and fluid actuated cylinder can be removed from the tractor as a unit. In other words, all of these parts have the same and common attaching means for their attachment to an attaching portion formed on the tractor.
[003] Conventionally, the rockshaft is manufactured as a solid part with higher diameter in order to bear the load acting on it. Though the solid rockshaft bears the load acting on it, manufacturing of the rockshaft as a solid part increases the overall weight of the lift housing assembly. Conventionally, the rockshaft is made up of material having elongation property as it has to sustain fatigue life for pulsating load conditions. If the rockshaft is forged it will have increased cost as there will be machining cost addition. Another method of manufacturing the rockshaft is radial forging. However, the radial forging also incurs high manufacturing costs.
[004] Therefore, there exists a need for a method of manufacturing a rockshaft for a vehicle, which obviates the aforementioned drawbacks.
OBJECTS
[005] The principal object of an embodiment of this invention is to provide a method of manufacturing a rockshaft for a lift housing of a vehicle.
[006] Another object of an embodiment of this invention is to provide a method of manufacturing a hollow rockshaft.
[007] Yet another object of an embodiment of this invention is to provide a method of manufacturing a hollow rockshaft having lesser weight compared to the conventional rockshaft.
[008] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF DRAWINGS
[009] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0010] FIG. 1a and 1b depicts a perspective view and front view of a hollow rockshaft for a lift housing of a vehicle, according to an embodiment of the invention as disclosed herein;
[0011] FIG. 2 depicts an exploded view of the lift housing assembly for the vehicle having the hollow rockshaft, according to an embodiment of the invention as disclosed herein;
[0012] FIG. 3 depicts an sectional view of the hollow rockshaft, according to an embodiment of the invention as disclosed herein; and
[0013] FIG. 4 is a flowchart of a method of manufacturing a hollow rockshaft, according to an embodiment of the invention as disclosed herein.
DETAILED DESCRIPTION
[0014] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0015] The embodiments herein achieve a method of manufacturing a rockshaft for a lift housing of a vehicle. Further, the embodiments herein achieve a method of manufacturing a hollow rockshaft. Referring now to the drawings, and more particularly to FIGS. 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0016] FIG. 1a and 1b depicts a perspective view and front view of a hollow rockshaft for a lift housing of a vehicle, according to an embodiment of the invention as disclosed herein. In an embodiment, the rock shaft 102 manufactured by the method 200 includes the rock-shaft having a central bore 104. In an embodiment, the rock shaft 102 is also referred as hollow rock shaft 102. In an embodiment, the hollow rock shaft 102 includes an input portion having a length L3 and diameter D3, a supporting portion having length L2 extending on both sides of the input portion and having a diameter D2, and an output portion having a length L1 extending away from the supporting portion and having a diameter D1.
[0017] The embodiments herein provides an implement controlling rock shaft 102 which is mounted having the central bore 104 (also referred as hollow portion 104) suitably journaled in a cover housing 106 which is bolted to a body of the vehicle in overlying relationship. At each lateral extremity of rock shaft 102, a pair of lifting crank arms 108 is mounted. In an embodiment, the hollow portion of the rock shaft 102 is locked and closed using a circlip 108 and a welch plug 110 as shown in FIG. 2. However, it is also within the scope of the invention to provide any other component for closing and locking the ends of rockshaft as can be deduced from the description and corresponding drawings.
[0018] FIG. 4 is a flowchart of a method of manufacturing a hollow rockshaft, according to an embodiment of the invention as disclosed herein. A method 1000 of manufacturing a rockshaft 102 for vehicles is provided. At step 1002, the method includes casting a rock shaft 102 by pouring a predetermined material into a mould of predetermined shape and size. At step 1004, the method includes subjecting the rock shaft 102 to a predetermined heat treatment process subsequent to casting.
[0019] In an embodiment, the method includes casting a rock shaft 102 by pouring a predetermined material into a mould of predetermined shape and size. In an embodiment, the mould is made up of an inner core which is made up of a first predetermined material and having an outer diameter d1. In an embodiment, the first predetermined material is selected from at least one of sand, glass and the like. In an embodiment, the outer diameter d1 corresponds to an inner diameter of the rockshaft 102. In an embodiment, for example the diameter d1 may range between 32-34 mm.
[0020] In an embodiment, the mould further includes an outer core concentrically surrounding the inner core made up of second predetermined material and having an inner diameter d2. In an embodiment, the second predetermined material is selected from at least one of sand, glass and the like. In an embodiment, the inner diameter d2 corresponds to an outer diameter of the rockshaft 102. In an embodiment, the outer core and the inner core defines a cavity for retaining the predetermined material.
[0021] In an embodiment, a plurality of chaplets 112 is disposed between the inner core and the outer core as shown in FIG. 3 to avoid bending of the inner core and the outer core. In an embodiment, the plurality of chaplets are made up of material same as the predetermined material of the rockshaft. In an embodiment, the rockshaft is casted as hollow profile by single core, there is a chance of warpage (bend) of the inner core or the outer core due to component length of 487mm. The warpage may be approximately 2 to 3 mm all over the length of the rockshaft 102. To avoid core bend, the plurality chaplets 112 are used instead of cored hole. In an embodiment, strength of chaplets 112 is equal to the strength of predetermined material. In an embodiment, the mould further includes a runner defined at a predetermined location of the mould for pouring the predetermined material into the cavity defined by the outer core and the inner core.
[0022] In an embodiment, the method includes subjecting the rock shaft 102 to a predetermined heat treatment process subsequent to casting. In an embodiment, the predetermined heat treatment process is austempering. In an embodiment, the predetermined heat treatment process is austempering of ductile iron. In an embodiment, the rockshaft 102 is heated to a temperature ranging from 350? to 450? centigrade in the austempering process. In an embodiment, the predetermined heating process is done using a furnace where the casted rockshaft 102 is subjected to a heat of 400? C and then allowed to cool at room temperature. In an embodiment, for example SG Iron castings may be heat treated with controlled conditions for ADI Treatment. However, it is also within the scope of the invention to provide any other heat treatment process for inducing strength and other properties of material to the rockshaft as can be deduced from the description and corresponding drawings.
[0023] In an embodiment, the method further includes subjecting the rock shaft 102 to a shot peening process at predetermined locations subsequent to the heat treatment process. In an embodiment, the the shot peening process is exerted at predetermined locations of the rockshaft 102 to achieve a predetermined hardness case-depth. In an embodiment, the shot peening process induces a surface hardness ranging 40-60 HRC for a 0.2 mm case depth.
[0024] In an embodiment, the rockshaft 102 is made up of ferrous material. In an embodiment, the rockshaft 102 is made up of SG iron. However, it is also within the scope of the invention to provide any other material having strength and other properties of material to manufacture the rockshaft as can be deduced from the description and corresponding drawings. In an embodiment, the rockshaft includes plurality of splines 114 defined at outer surface of the output portion.
[0025] In an embodiment, for example the material property used for the rockshaft may includes shaft tensile strength (T.S.) 850 MPa, yield strength (Y.S.) 550 MPa, elongation 10%, surface T.S. 1460 MPa, surface Y.S. 1168 Mpa, surface hardening: 45-55 Rc for 0.2mm depth throughout, including splines and excluding end length of 0.5”, hardness – 269-321BHN.
[0026] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:STATEMENT OF CLAIMS
I/We claim,
1.A method 1000 of manufacturing a rockshaft 102 for vehicles, the method 100 comprising steps of:
casting a rock shaft 102 by pouring a predetermined material into a mould of predetermined shape and size; and
subjecting the rock shaft 102 to a predetermined heat treatment process subsequent to casting,
wherein
the predetermined heat treatment process is austempering, and
the rockshaft 102 includes a central bore 104.
2.A method 2000 of manufacturing a rockshaft 102 for vehicles, the method comprising steps of:
casting a rock shaft 102 by pouring a predetermined material into a mould of predetermined shape and size;
subjecting the rock shaft 102 to a predetermined heat treatment process subsequent to casting; and
subjecting the rock shaft 102 to a shot peening process at predetermined locations subsequent to the heat treatment process,
wherein
the rockshaft 102 includes a central bore 104, and
the rock shaft 102 is made of ferrous material; and
the predetermined heat treatment process is austempering of ductile iron, and
the shot peening process is exerted at predetermined locations of the rockshaft 102 to achieve a predetermined hardness case-depth.
3.The method 100 as claimed in claim 1, wherein the mould is made up of:
an inner core made up of a first predetermined material and having an outer diameter D1;
an outer core concentrically surrounding the inner core made up of second predetermined material and having an inner diameter D2;
the outer core and the inner core defining a cavity for retaining the predetermined material;
a plurality of chaplets 112 disposed between the inner core and the outer core; and
a runner defined at a predetermined location of the mould for pouring the predetermined material into the cavity defined by the outer core and the inner core,
wherein
the plurality of chaplets 112 are made up of material same as the predetermined material of the rockshaft.
4.The method 100 as claimed in claim 1, wherein the rockshaft 102 is heated to a temperature ranging from 350? to 450? centigrade in the austempering process.
5.The method 100 as claimed in claim 1, wherein the rockshaft 102 is made up of SG Iron.
6.The method 200 as claimed in claim 2, wherein the shot peening process induces a surface hardness ranging 40-60 HRC for a predetermined case depth.