DESC:Field of the invention
The present invention relates to forks for automobile and more particularly, to a front fork outer tube for a two wheeler and casting method thereof.
Background of the invention
In prior art as shown in figure 1, a front fork outer tube is used to mount the axle of a front wheel in a two wheeler. Aiming this hole at the bottom of the front fork is closely tolerated. The front fork outer body is basically made up of aluminum alloy material using gravity die cast for strength purposes. The process of die casting in the art, the core can be inserted along the axis of the material flow. It is difficult to provide core in the perpendicular direction of material flow. The axle hole position is hence marked on the outer body when it is moulded. Then outer tube is mounted on a vertical machining centre and the hole is drilled and bored to size. Since axle hole is one of the important parameter to be maintained in terms of perpendicularity, orientation and finish, the same needs to be machined in different steps which in turn increases operation time. Thus, machining of the outer tube results in additional loss of material, increasing cycle time to make the part and also adds the cost of machining in final manufacturing of the outer tube.
Accordingly, there is a need of an improved front fork outer tube and it’s casting method to overcome the above mentioned drawbacks of the prior art.
Object of the invention
An object of the present invention is to reduce the loss of material by the way of machining.
Another object of the present invention is to reduce the cycle time to make the part.
Still another object of the present invention is to reduce machining allowance on outer tube to operate at higher cutting parameters to meet the required specifications with lesser load on the spindle.
Yet another object of the present invention is to avoid the cost of machining.
Summary of the invention
The present invention provides casting method for a front fork outer tube for two wheeler vehicle. The cylindrically shaped outer tube, open at one end has an axle hole at the closed end, perpendicular to its length and connecting diametrically opposite ends. In a casting process, an additional pin is placed in a die cast, just before moulding, perpendicular to the flow of material. The outer tube is formed along with the axle hole at the closed end, and can be directly bore machined to the required size from pre-moulded hole.
Brief description of the drawings
The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,
Figure 1 shows a top and a side view of a front fork outer tube, in a prior art; and
Figure 2 shows a top and a side view of a front fork outer tube, in accordance with the present invention.
Detail description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a casting method for a front fork outer tube for two wheeler vehicles. The front fork outer tube has an axle hole near the closed end of outer tube and perpendicular to the length of the outer tube. Accordingly a method of casting outer tube with prefinished axle hole comprises of placing a pin in the position of axle hole, at the closed end of the die cast and in a direction perpendicular to the flow of molten alloy. The moulded casting once come out of the die forms an axle hole (10).
The present invention is illustrated with reference to the accompanying drawings, wherein numbers indicated in the bracket represent the components of the invention throughout the description.
Referring to figure 2, a top view and a side view of a front fork outer tube (100) (hereinafter referred as ‘the outer tube (100)’) in accordance with the present invention is shown. The outer tube (100) is made of high strength aluminum alloy. The outer tube (100) is a cylindrically shaped structure having opening at one end. The outer tube (100) has at least one axle hole (10) at the closed end, perpendicular to the length of outer tube (100) and connecting diametrically opposite ends.
The outer tube (100) of the present invention is cast in a ground die cast using a high strength aluminum alloy. Casting process of the outer tube (100) of the present invention comprises placing a pin in the position of axle hole which is located in the ground die cast mould, at the closed end of the die cast and in a direction perpendicular to the flow of molten alloy. The moulded casting once come out of the die forms an axle hole (10). The axle hole (10) is configured to be in perpendicular direction of material flow and able to achieve the desired property and results. The outer tube (100) produced from the casting process of the present invention facilitates to directly bore the axle hole on the casting which is pre bore casting to get appropriate size and accuracies. With this pre-hole condition, the machining process cycle time and tool life can be improved by at least 30% and the casting process is observed to save 30 grams of raw material per outer tube (100).
Advantages of the invention
• The outer tube (100) and casting method reduces the loss of material by the way of machining.
• The outer tube (100) and casting method reduces the cycle time by at least 30% for the particular hole to make the part.
• The outer tube (100) and casting method improves tool life in turn reducing the cost of machining.
• The casting method saves 30 grams of raw material per outer tube (100).
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.
,CLAIMS:
1. Casting method for a front fork outer tube (100), the method comprising,
placing a pin at a closed end of a ground die cast, in a direction perpendicular to the flow of molten alloy;
pouring the molten alloy into the ground die cast;
cooling the ground die cast and removing the front fork outer tube from the ground die cast;
removing the pin;
characterized in that the pin placed at the closed end of the ground die cast in a direction perpendicular to the flow of molten alloy, forms an axle hole (10) ) at the closed end of the front fork outer tube (100), perpendicular to the length of the front fork outer tube (100).
2. The casting method as claimed in claim 1 wherein the molten alloy is a high strength aluminum alloy