Patent ID: 12187073

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

To fully understand the present disclosure, the operational advantages of the present disclosure, and the object achieved by practicing the present disclosure, reference should be made to the accompanying drawings showing exemplary embodiments of the present disclosure and the contents described in the accompanying drawings.

In describing the exemplary embodiments of the present disclosure, a description of well-known technologies or repetitive descriptions that can unnecessarily obscure the gist of the present disclosure is reduced or omitted.

Terms such as a radial direction, a circumferential direction, and a width direction used in the present disclosure are defined based on a rim portion230. Therefore, the radial direction, the circumferential direction, and the width direction mean the radial direction of the rim portion230, the circumferential direction of the rim portion230, and the width direction of the rim portion230, respectively.

When a component, device, element, or the like of the present disclosure is described as having a purpose or performing an operation, function, or the like, the component, device, or element should be considered herein as being “configured to” meet that purpose or to perform that operation or function.

Referring toFIGS.1to6, a method for manufacturing a one-piece wheel by forging according to an exemplary embodiment of the present disclosure produces an integral forging200including: a disc portion210, the rim portion230, and an annular protrusion214using a forging method (S10). Thereafter, the method produces an outer bend310by bending the annular protrusion214using a flow-forming process (S20). The method can produce the integral forging200and then, flow-form the rim portion230(S30). The method produces the outer bend310and then, welds one end of the outer bend310and one side of the rim portion230to form a hollow portion330(S40). In addition, the method produces the outer bend310and then, can form a resonance hole510in the outer bend310(S50). In addition, the method forms the resonance hole510, and then, can additionally perform a boring process to adjust the depth of the resonance hole510.

Hereinafter, a low-noise type one-piece wheel and a manufacturing method thereof according to an exemplary embodiment of the present disclosure are described in more detail.

Referring toFIG.2, the integral forging200according to the exemplary embodiment of the present disclosure includes: the disc portion210, the annular protrusion214protruding from the disc portion210, and the rim portion230.

The disc portion210includes: a hub211coupled to a vehicle body of the vehicle, a flange213formed to be spaced apart from the outer circumference of the hub211, and a temporary spoke212disposed at equal intervals to connect the hub211and the flange213.

The wheel made by using the casting method can have the non-uniform alloy composition and have porosity defects due to the gas permeated during the solidification process.

The integral forging200according to the exemplary embodiment of the present disclosure is produced by using the forging process to compensate for this disadvantage of the casting method. To produce the integral forging200, a billet is disposed on a lower mold having a shape corresponding to a shape of a part of a lower portion of the integral forging200and heated. The material of the billet can be any one of an aluminum alloy, a magnesium alloy, or a steel. The integral forging200is produced by moving downward an upper mold having a shape corresponding to a shape of a part of an upper portion of the one-piece wheel with the hollow structure toward the lower mold using a press under a hot condition to pressurize an upper surface of the billet. The upper mold and the lower mold are used to manufacture the integral forging200, and a side mold can additionally be used.

As described above, the integral forging200produced in the forging method has a uniform crystal structure, and occurs no pores or material shrinkage therein. Therefore, the integral forging200produced in the forging method has stronger shear strength and stiffness and a longer fatigue life than those of the casting produced in the casting method.

Next, the annular protrusion214is formed to protrude from one side of the disc portion210. The annular protrusion214can protrude from one side of the disc portion210toward the rim portion230. This is to smoothly separate the upper mold and the lower mold from the integral forging200after forging.

In other words, the present disclosure provides the method for manufacturing the one-piece wheel by forging, and it is impossible to form the protrusion in an outer direction of the rim as in the casting, and the protrusion should be necessarily formed to protrude downward toward the rim portion230.

Referring toFIGS.3A to6, the outer bend310forms the hollow portion330together with a part of the rim portion230. The hollow portion330can reduce the noise generated from the wheel due to a principle of a Helmholtz resonator.

The Helmholtz resonator includes an inner space and a neck portion communicating the inner space and an outer region of the inner space. The Helmholtz resonator can constitute a vibration system as a whole. Specifically, the air of the neck portion and the air of the inner space in the Helmholtz resonator can serve as a mass and a spring of a spring-mass model, respectively. When resonance occurs in the Helmholtz resonator, the air in the neck portion intensely moves in and out of the neck portion. In this case, continuous friction can occur between a tube wall of the neck portion and the air of the neck portion. Vibration energy can be converted into thermal energy by this friction, and therefore, the noise generated from the wheel can be canceled or reduced. At this time, a frequency of the noise canceled or reduced is determined by the volume of the inner space of the Helmholtz resonator, and the length and cross-sectional area of the neck portion.

In addition, the hollow portion330serves as the inner space of the Helmholtz resonator to reduce the noise generated from the wheel. The annular protrusion214can be spaced apart from the rim portion230by a predetermined interval in a radially outside direction of the disc portion210to correspond to the radial thickness of the hollow portion330.

In addition, the method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure can include a pre-processing process of the hollow portion330of processing the rim portion230so that the hollow portion330has a volume suitable for the frequency to be resonated after producing the integral forging200.

The method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure can include a process of pre-processing the rim portion230to precisely measure the dimension of an inner surface of the rim portion230after producing the integral forging200.

In addition, the method for manufacturing the one-piece wheel by forging according to an exemplary embodiment of the present disclosure can include a step of pre-processing the outer bend310so that the annular protrusion214is smoothly bent before producing the outer bend310by bending the annular protrusion214using the flow-forming process.

In addition, the method for manufacturing the one-piece wheel by forging can include a step of pre-heating the rim portion230using a pre-heater (not shown) so that flow-forming process of the rim portion230can be performed more smoothly by smoothing the material after producing the integral forging200.

Referring toFIGS.3A to3C, according to the exemplary embodiment of the present disclosure, the outer bend310is produced by bending the annular protrusion214using the flow-forming process after separating the integral forging200from the mold (S20). The outer bend310can be produced while the integral forging200is flow-formed. In the process of producing the outer bend310, one end of the annular protrusion214is bent to face the rim portion230. A ring-shaped space formed by an outer circumferential surface of the rim portion230and an inner surface of the outer bend310becomes the hollow portion330serving as the inner space of the Helmholtz resonator thereafter.

The method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure can include: a process of flow-forming the rim portion230(S30) after producing the integral forging200. When the shape of the rim portion230is formed while the rim part230is flow-formed, the strength of the rim portion230is strengthened. The method for manufacturing the one-piece wheel has the advantage of strengthening the mechanical properties of the product including rigidity twice, including the forging process and the flow-forming process. Here, while a case where the rim portion230is flow-formed after the outer bend310is produced is described, the method for manufacturing the one-piece wheel by low forging according to the exemplary embodiment of the present disclosure is not limited thereto, and includes a case where the rim portion230is flow-formed before the outer bend310is produced after the integral forging200is produced.

Referring toFIGS.3A to3C and4, the flow forming of the rim portion230can use a method for forming the rim portion230using a mandrel370and a roller390.FIG.3shows that a rotation axis of the roller390is not perpendicular to a rotation axis of the rim portion230, but the present disclosure is not limited thereto. For example, the rotation axis of the roller390according to the present disclosure can be configured to be perpendicular to the rotation axis of the wheel.

Meanwhile, since the temporary spoke212is formed on the inner circumference of the rim portion230, the integral forging200can be stably seated on the mandrel370. It is possible to inhibit or prevent the shape of the rim portion230from being distorted or twisted by the temporary spoke212even during the flow forming of the rim portion230by the roller390, thereby smoothly completing the flow forming of the rim portion230without defects of the product.

The process of producing the outer bend310and the process of flow-forming the rim portion230according to the exemplary embodiment of the present disclosure can be performed by using the same roller390. Since the process of bending the annular protrusion214and the process of flow-forming the rim portion230are performed by using the same roller390, two processes can be performed continuously or performed simultaneously. As a result, it is possible to reduce the manufacturing equipment cost and to reduce the process time.

Referring toFIGS.3A to3C, the process of flow-forming the rim portion230following the process of producing the outer bend310can be performed continuously while the same roller390is moved from the disc portion210side to the rim portion230side. However, the method for manufacturing the one-piece wheel by forging according to the present disclosure is not limited to moving the roller390from the disc portion210side to the rim portion230side, and includes all exemplary embodiments in which the rim portion230is flow-formed and the outer bend310is produced by the same roller390. For example, referring toFIG.4, the method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure includes a case of continuously performing the process of flow-forming the rim portion230followed by the process of producing the outer bend310while the roller is moved from the rim portion230side to the disc portion210side.

The method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure includes a process of welding one end of the outer bend to one side of the rim portion. As a result, the hollow portion serving as the inner space of the Helmholtz resonator is formed.

The method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure forms the hollow portion330having the noise reduction function by friction-stir-welding one end of the outer bend310to one side of the rim portion230.

Referring toFIG.6, the hollow portion330having a ring shape is formed by bending one end of the annular protrusion214of the integral forging200to be in contact with one side of the rim portion230, and then, the annular protrusion214and the outer circumference of the rim portion230, which are in contact with each other, can be friction-stir-welded by using a friction stir welding tool530.

In one embodiment, the friction stir welding tool530includes a welding tool531operated to rotate and a lift pin533coupled to the center of the welding tool531and formed to protrude downward. Here, the lift pin533can be configured to perform a moving-up operation through a cylinder (not shown). For the friction stir welding between the outer bend310and the rim portion230, the end of the lift pin533is inserted into a position where the outer bend310and the rim portion230face each other. Then, the lift pin533coupled to the welding tool531rotates in a state of being inserted into a welded surface, thereby causing a plastic flow of the material due to frictional heat on the welded surface. Therefore, the solid-state welding of the outer bend310and the rim portion230is performed. According to the rotation of the outer bend310and the rim portion230, the welding by the friction stir welding tool530can be automatically performed along a welded interface, and therefore, completed at a point where the outer bend310and the rim portion230rotate by 360 degrees. At this time, the lift pin533can be spaced apart from the welded surface at the point where friction stirring is completed through the upward operation of the lift pin533. As a result, it is possible to prevent an end hole from being formed on the welded surface where the outer bend310and the rim portion230are welded to each other. Therefore, it is possible to minimize a heat-affected portion, thereby securing the durability and reliability of the wheel.

A main processing process of additionally processing the integral forging200can be performed to have the precise dimension according to the specifications of the drawings using processing equipment such as a reaming machine (not shown) after welding the outer bend310and the rim portion.

In addition, a plating process of spraying a particulate material or a liquid paint on the surface of the product can be additionally performed to prevent contamination or corrosion of the material after welding the outer bend310and the rim portion.

The method for manufacturing the one-piece wheel by forging according to the exemplary embodiment of the present disclosure can further include: forming the resonance hole510in the outer bend310after the outer bend310is produced (S50). The resonance hole510formed here serves as the neck portion of the Helmholtz resonator. According to an exemplary embodiment of the present disclosure, the resonance hole510may be formed after one end of the outer bend310is welded to one side of the rim portion. A plurality of resonance holes510can be formed, and four resonance holes510can be formed to obtain the excellent noise reduction effect in a wide range of the resonance frequency band by adjusting the volume of the hollow portion330serving as the inner space of the Helmholtz resonator.

A plurality of hollow portions330according to the exemplary embodiment of the present disclosure can be formed. Referring toFIGS.5A-5B, the plurality of hollow portions330can be formed to be separated into plural by a confining wall400dividing the respective hollow portions330. At this time, the confining wall400can be formed on the outer circumference of a lower portion of the disc portion210, and the outer bend310can be in close contact with the confining wall400so that the confining wall400separates the respective hollow portions330. When the outer bend310is in close contact with the confining wall400, the airflow between two neighboring hollow portions330can be completely blocked. In other words, each hollow portion330communicates with the outside only through the resonance hole510. As a result, it is possible to improve the noise reduction effect using the hollow portion330.

One resonance hole510according to the exemplary embodiment of the present disclosure can be formed in each of the hollow portions330. For example, if the number of resonance holes510is set as four and the resonance holes510are configured at equal intervals, the hollow portion330can be configured to be divided into four equal to the number of resonance holes510. Such a configuration can be easily implemented by configuring four confining walls400on the outer circumference of the lower portion of the disc portion210so that the confining wall400is in close contact with the welded portion of the rim portion230.

In one embodiment, the plurality of hollow portions330can have the same volumes. Alternatively, at least two hollow portions330among the plurality of hollow portions330according to the exemplary embodiment of the present disclosure can have different volumes. When the plurality of hollow portions330have the same volume, it is possible to intensively offset target frequencies corresponding to the same volume, and if they have different volumes, it is possible to obtain the noise reduction effect in a wider range of resonance frequency band.

The confining walls400for forming the plurality of hollow portions330can be configured to be disposed at the same or different intervals so that the hollow portions330have the same or different volumes depending upon the target frequencies at which the respective hollow portions330separated by the confining wall400intends to offset.

Therefore, according to the method for manufacturing the low-noise type one-piece wheel according to the exemplary embodiment of the present disclosure, it is possible to effectively reduce the road noise even without mounting a separate device to the wheel.

In addition, when the resonance hole510is formed in the outer bend310as described above, it is natural that the generally performed pre-processing can be performed to meet the disc portion210produced by forging to the precise dimension.

A method for manufacturing a one piece wheel according to the exemplary embodiment of the present disclosure can include: a process of boring the resonance hole510after the resonance hole510is formed in the hollow portion330. The resonance hole510serves as the neck portion in the Helmholtz resonator, and the resonance frequency of the Helmholtz resonator is determined by the length of the neck portion and the volume of the inner space. At this time, this is to adjust the depth of the neck so that resonance occurs at the frequency to be attenuated within the hollow portion330.

Meanwhile, the outer bend310should be produced by bending the annular protrusion214protruding in the radial direction of the rim portion230on the outer circumferential surface of the rim portion230before the resonance hole510is formed. The annular protrusion214formed on the outer circumferential surface of the rim portion230can be produced in the process of producing the integral forging200.

The content of the present disclosure includes: a one-piece wheel manufactured by the aforementioned method for manufacturing the one-piece wheel having the hollow structure for the noise reduction.

The low-noise type one-piece wheel according to the exemplary embodiment of the present disclosure includes: the disc portion210, the rim portion230, the hollow portion330formed on the outer circumferential surface of the rim portion230, and the resonance hole510. At this time, the inner circumferential surface of the hollow portion330can be formed of a part of the outer circumferential surface of the rim portion230and the inner surface of the outer bend310protruding from the disc portion210. Here, the resonance hole510is formed in the outer bend310. The hollow portion330formed on the outer circumferential surface of the rim portion230serves as the inner space of the Helmholtz resonator, and the resonance hole510serves as the neck portion of the Helmholtz resonator, thereby reducing the road noise. In addition, the outer bend310can be formed to protrude from the disc portion210, thereby being easily manufactured in the forging method.

The plurality of hollow portions330according to the exemplary embodiment of the present disclosure can be formed. The plurality of hollow portions330can have the same volumes. In another embodiment, at least two hollow portions330among the plurality of hollow portions330can have different volumes. If the plurality of hollow portions330have the same volumes, it is possible to intensively offset the target frequencies corresponding to the same volumes, and if they have different volumes, it is possible to obtain the noise reduction effect in the wider range of resonance frequency band. At this time, the plurality of hollow portions330can be separated from the neighboring hollow portions330by the confining wall400. Two neighboring hollow portions330can be separated by bringing the outer bend310in close contact with the confining wall400. The airflow between the two neighboring hollow portions330can be completely blocked. In other words, each hollow portion330communicates with the outside only through the resonance hole510. As a result, it is possible to improve the noise reduction effect using the hollow portion330.

The present disclosure has been described above with reference to the exemplary drawings, but it is apparent to those having ordinary skill in the art that the present disclosure is not limited to the exemplary embodiment described, and can be variously modified and changed without departing from the spirit and scope of the present disclosure. Therefore, these modifications and changes should be included in the scope of the present disclosure.